diff --git a/runtime/syntax/j.vim b/runtime/syntax/j.vim
index b19247b..20063a2 100644
--- a/runtime/syntax/j.vim
+++ b/runtime/syntax/j.vim
@@ -2,31 +2,36 @@
 " Language:	J
 " Maintainer:	David Bürgin <676c7473@gmail.com>
 " URL:		https://github.com/glts/vim-j
-" Last Change:	2014-03-17
+" Last Change:	2014-04-05
 
 if exists('b:current_syntax')
   finish
 endif
 
+let s:save_cpo = &cpo
+set cpo&vim
+
 syntax case match
 syntax sync minlines=50
 
+syntax cluster jStdlibItems contains=jStdlibNoun,jStdlibAdverb,jStdlibConjunction,jStdlibVerb
+syntax cluster jPrimitiveItems contains=jNoun,jAdverb,jConjunction,jVerb,jCopula
+
 syntax match jControl /\<\%(assert\|break\|case\|catch[dt]\=\|continue\|do\|else\%(if\)\=\|end\|fcase\|for\|if\|return\|select\|throw\|try\|whil\%(e\|st\)\)\./
 syntax match jControl /\<\%(for\|goto\|label\)_\a\k*\./
 
-" Standard library names defined in the z locale. A few verbs need to be
-" defined with ":syntax match" because they would otherwise take precedence
-" over the corresponding jControl items.
-syntax keyword jNoun ARGV BINPATH CR CRLF DEL Debug EAV EMPTY FF FHS IF64 IFIOS IFJCDROID IFJHS IFQT IFRASPI IFUNIX IFWIN IFWINCE IFWINE IFWOW64 JB01 JBOXED JCHAR JCMPX JFL JINT JPTR JSIZES JSTR JTYPES JVERSION LF LF2 TAB UNAME UNXLIB adverb andurl conjunction dbhelp dyad libjqt monad noun verb
-syntax keyword jAdverb define each every fapplylines inv inverse items leaf rows table
-syntax keyword jConjunction bind cuts def on
-syntax keyword jVerb AND Endian IFDEF Note OR XOR alpha17 alpha27 anddf android_exec_host andunzip apply boxopen boxxopen bx calendar cd cdcb cder cderx cdf charsub chopstring clear coclass cocreate cocurrent codestroy coerase cofind cofindv cofullname coinfo coinsert coname conames conew conl conouns conounsx copath copathnl copathnlx coreset costate cut cutLF cutopen cutpara datatype dbctx dberm dberr dbg dbjmp dblocals dblxq dblxs dbnxt dbq dbr dbret dbrr dbrrx dbrun dbs dbsig dbsq dbss dbst dbstack dbstk dbstop dbstopme dbstopnext dbstops dbtrace dbview deb debc delstring detab dfh dir dircompare dircompares dirfind dirpath dirss dirssrplc dirtree dirused dlb dltb dltbs dquote drop dropafter dropto dtb dtbs echo empty endian erase evtloop exit expand f2utf8 fappend fappends fboxname fc fcopynew fdir ferase fetch fexist fexists fgets file2url fixdotdot fliprgb fmakex foldpara foldtext fpathcreate fpathname fputs fread freadblock freadr freads frename freplace fsize fss fssrplc fstamp fstringreplace ftype fview fwrite fwritenew fwrites getargs getdate getenv getqtbin hfd hostpathsep ic install iospath isatty isotimestamp isutf8 jcwdpath joinstring jpathsep jsystemdefs list ljust load loadd mema memf memr memw nameclass namelist names nc nl pick quote require rjust rplc script scriptd setbreak show sign sminfo smoutput sort split splitnostring splitstring ss startupandroid startupconsole startupide stderr stdin stdout stringreplace symdat symget symset take takeafter taketo timespacex timestamp timex tmoutput toCRLF toHOST toJ todate todayno tolower topara toupper tsdiff tsrep tstamp type ucp ucpcount unxlib usleep utf8 uucp valdate wcsize weekday weeknumber weeksinyear winpathsep
-syntax match   jVerb /\<\%(assert\|break\|do\)\>\.\@!/
+" Standard library names. A few names need to be defined with ":syntax match"
+" because they would otherwise take precedence over the corresponding jControl
+" and jDefineExpression items.
+syntax keyword jStdlibNoun ARGV BINPATH CR CRLF DEL Debug EAV EMPTY FF FHS IF64 IFIOS IFJCDROID IFJHS IFQT IFRASPI IFUNIX IFWIN IFWINCE IFWINE IFWOW64 JB01 JBOXED JCHAR JCMPX JFL JINT JPTR JSIZES JSTR JTYPES JVERSION LF LF2 TAB UNAME UNXLIB andurl dbhelp libjqt
+syntax keyword jStdlibAdverb define each every fapplylines inv inverse items leaf rows table
+syntax keyword jStdlibConjunction bind cuts def on
+syntax keyword jStdlibVerb AND Endian IFDEF Note OR XOR alpha17 alpha27 anddf android_exec_host andunzip apply boxopen boxxopen bx calendar cd cdcb cder cderx cdf charsub chopstring clear coclass cocreate cocurrent codestroy coerase cofind cofindv cofullname coinfo coinsert coname conames conew conl conouns conounsx copath copathnl copathnlx coreset costate cut cutLF cutopen cutpara datatype dbctx dberm dberr dbg dbjmp dblocals dblxq dblxs dbnxt dbq dbr dbret dbrr dbrrx dbrun dbs dbsig dbsq dbss dbst dbstack dbstk dbstop dbstopme dbstopnext dbstops dbtrace dbview deb debc delstring detab dfh dir dircompare dircompares dirfind dirpath dirss dirssrplc dirtree dirused dlb dltb dltbs dquote drop dropafter dropto dtb dtbs echo empty endian erase evtloop exit expand f2utf8 fappend fappends fboxname fc fcopynew fdir ferase fetch fexist fexists fgets file2url fixdotdot fliprgb fmakex foldpara foldtext fpathcreate fpathname fputs fread freadblock freadr freads frename freplace fsize fss fssrplc fstamp fstringreplace ftype fview fwrite fwritenew fwrites getargs getdate getenv getqtbin hfd hostpathsep ic install iospath isatty isotimestamp isutf8 jcwdpath joinstring jpathsep jsystemdefs list ljust load loadd mema memf memr memw nameclass namelist names nc nl pick quote require rjust rplc script scriptd setbreak show sign sminfo smoutput sort split splitnostring splitstring ss startupandroid startupconsole startupide stderr stdin stdout stringreplace symdat symget symset take takeafter taketo timespacex timestamp timex tmoutput toCRLF toHOST toJ todate todayno tolower topara toupper tsdiff tsrep tstamp type ucp ucpcount unxlib usleep utf8 uucp valdate wcsize weekday weeknumber weeksinyear winpathsep
+syntax match jStdlibNoun /\<\%(adverb\|conjunction\|dyad\|monad\|noun\|verb\)\>/
+syntax match jStdlibVerb /\<\%(assert\|break\|do\)\>\.\@!/
 
-syntax region jString oneline start=/'/ skip=/''/ end=/'/
-
-" Number patterns. Matching J numbers is difficult. The regular expression
-" used for the general case roughly embodies this grammar sketch:
+" Numbers. Matching J numbers is difficult. The regular expression used for
+" the general case roughly embodies this grammar sketch:
 "
 "     BASE     := /_?\d+(\.\d*)?([eE]_?\d+)?/
 "     RATIONAL := BASE  |  BASE r BASE
@@ -43,21 +48,87 @@
 syntax match jNumber /\<_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\%(\%(r_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\%([px]_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\%(r_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\)\=\)\=\)\|\%(\%(j\|a[dr]\)_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\%([px]_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\%(\%(j\|a[dr]\)_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\)\=\)\=\)\|\%([px]_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\%(\%(j\|a[dr]\|r\)_\=\d\+\%(\.\d*\)\=\%([eE]_\=\d\+\)\=\)\=\)\)\=/
 syntax match jNumber /\<_\=\d\+\%([eE]\d\+\)\=b_\=[0-9a-z]\+/
 syntax match jNumber /\<__\=\>/
+syntax match jNumber /\<_\./
 syntax match jNumber /\<_\=\d\+x\>/
 
-syntax keyword jTodo TODO FIXME XXX contained
+syntax region jString oneline start=/'/ skip=/''/ end=/'/
+
+syntax keyword jArgument contained x y u v m n
+
+" Primitives. Order is significant both within the patterns and among
+" ":syntax match" statements. Refer to "Parts of speech" in the J dictionary.
+syntax match jNoun /\<a[.:]/
+syntax match jAdverb /[}~]\|[/\\]\.\=\|\<\%([Mbft]\.\|t:\)/
+syntax match jConjunction /"\|`:\=\|[.:@&][.:]\=\|&\.:\|\<\%([dDHT]\.\|[DLS]:\)/
+syntax match jVerb /[=!\]]\|[\^?]\.\=\|[;[]:\=\|{\.\|[_/\\]:\|[<>+*\-%$|,#][.:]\=\|[~}"][.:]\|{\%[::]\|\<\%([ACeEiIjLor]\.\|p\.\.\=\|[ipqsux]:\|0:\|_\=[1-9]:\)/
+syntax match jCopula /=[.:]/
+syntax match jConjunction /;\.\|\^:\|![.:]/
+
+" Explicit noun definition. The difficulty is that the define expression
+" "0 : 0" can occur in the middle of a line but the jNounDefine region must
+" only start on the next line. The trick is to split the problem into two
+" regions and link them with "nextgroup=".
+syntax region jNounDefineStart
+    \ matchgroup=jDefineExpression start=/\<\%(0\|noun\)\s\+\%(\:\s*0\|def\s\+0\|define\)\>/
+    \ keepend matchgroup=NONE end=/$/
+    \ contains=@jStdlibItems,@jPrimitiveItems,jNumber,jString,jParenGroup,jParen,jComment
+    \ oneline skipempty nextgroup=jDefineEnd,jNounDefine
+" These two items must have "contained", which allows them to match only after
+" jNounDefineStart thanks to the "nextgroup=" above.
+syntax region jNounDefine
+    \ matchgroup=NONE start=/^/
+    \ matchgroup=jDefineEnd end=/^\s*)\s*$/
+    \ contained
+" This match is necessary in case of an empty noun definition
+syntax match jDefineEnd contained /^\s*)\s*$/
+
+" Explicit verb, adverb, and conjunction definition
+syntax region jDefine
+    \ matchgroup=jDefineExpression start=/\<\%([1-4]\|13\|adverb\|conjunction\|verb\|monad\|dyad\)\s\+\%(:\s*0\|def\s\+0\|define\)\>/
+    \ matchgroup=jDefineEnd end=/^\s*)\s*$/
+    \ contains=jControl,@jStdlibItems,@jPrimitiveItems,jNumber,jString,jArgument,jParenGroup,jParen,jComment,jDefineMonadDyad
+syntax match jDefineMonadDyad contained /^\s*:\s*$/
+
+" Paired parentheses. When a jDefineExpression such as "3 : 0" is
+" parenthesised it will erroneously extend jParenGroup to span over the whole
+" definition body. This situation receives a special treatment here.
+syntax match jParen /(\%(\s*\%([0-4]\|13\|noun\|adverb\|conjunction\|verb\|monad\|dyad\)\s\+\%(:\s*0\|def\s\+0\|define\)\s*)\)\@=/
+syntax match jParen contained /\%((\s*\%([0-4]\|13\|noun\|adverb\|conjunction\|verb\|monad\|dyad\)\s\+\%(:\s*0\|def\s\+0\|define\)\s*\)\@<=)/
+syntax region jParenGroup
+    \ matchgroup=jParen start=/(\%(\s*\%([0-4]\|13\|noun\|adverb\|conjunction\|verb\|monad\|dyad\)\s\+\%(:\s*0\|def\s\+0\|define\)\>\)\@!/
+    \ matchgroup=jParen end=/)/
+    \ oneline transparent
+
+syntax keyword jTodo contained TODO FIXME XXX
 syntax match jComment /NB\..*$/ contains=jTodo,@Spell
+
 syntax match jSharpBang /\%^#!.*$/
 
-highlight default link jControl Statement
-highlight default link jNoun Identifier
-highlight default link jAdverb Identifier
-highlight default link jConjunction Identifier
-highlight default link jVerb Function
-highlight default link jString String
-highlight default link jNumber Number
-highlight default link jTodo Todo
-highlight default link jComment Comment
-highlight default link jSharpBang PreProc
+highlight default link jControl           Statement
+highlight default link jStdlibNoun        Identifier
+highlight default link jStdlibAdverb      Function
+highlight default link jStdlibConjunction Function
+highlight default link jStdlibVerb        Function
+highlight default link jString            String
+highlight default link jNumber            Number
+highlight default link jNoun              Constant
+highlight default link jAdverb            Normal
+highlight default link jConjunction       Normal
+highlight default link jVerb              Normal
+highlight default link jCopula            Normal
+highlight default link jArgument          Identifier
+highlight default link jParen             Delimiter
+
+highlight default link jDefineExpression  Define
+highlight default link jDefineMonadDyad   Delimiter
+highlight default link jDefineEnd         Delimiter
+highlight default link jNounDefine        Normal
+
+highlight default link jTodo              Todo
+highlight default link jComment           Comment
+highlight default link jSharpBang         PreProc
 
 let b:current_syntax = 'j'
+
+let &cpo = s:save_cpo
+unlet s:save_cpo