Use thesaurus.com to look up synonyms and, if available, antonyms.
Moreover, it comes with an executable called tcom, which can be used to start
a search from the shell. The output is either plain-text (by default) or JSON.
$ npm install -g thesaurus-com
Or install it into the current directory, so you can play around with it:
$ npm install --save thesaurus-com
(The executable can then be found at ./node_modules/.bin/tcom.)
var tcom = require('thesaurus-com');
console.log(tcom.search('never'));
// { synonyms:
// [ 'at no time',
// 'don\'t hold your breath',
// 'forget it',
// 'nevermore',
// 'no way',
// 'not at all',
// 'not ever',
// 'not in any way',
// 'not in the least',
// 'not on your life',
// 'not under any condition' ],
// antonyms: [ 'always', 'forever' ] }$ tcom always
Synonyms: consistently, constantly, eternally, ever, everlastingly, evermore, for keeps, forevermore, in perpetuum, invariably, perpetually, regularly, repeatedly, till blue in the face, till cows come home, till hell freezes over, unceasingly, without exception
Antonyms: at no time, never
$ tcom -j always
{"synonyms":["consistently","constantly","eternally","ever","everlastingly","evermore","for keeps","forevermore","in perpetuum","invariably","perpetually","regularly","repeatedly","till blue in the face","till cows come home","till hell freezes over","unceasingly","without exception"],"antonyms":["at no time","never"]}