Webster's Tenth Collegiate dictionary lists synonyms of headword adjectives in two ways: in small caps in the main definition set, and at the end with the heading syn followed by a group of additional small cap synonyms. (The latter are selected to highlight the distinctions among the synonyms; for example lazy, indolent and slothful all mean "not easily aroused to activity", but lazy suggests a disinclination to take trouble, indolent suggests a love of ease, and slothful, a temperamental inability to act promptly.) Approximately 220 of the headword adjectives merit the syn treatment, and the one thousand synonyms they dissect represent about one-sixth of the headword adjectives.
Using this data, one can readily construct synonym chains (B is a synonym of A, C is a synonym of B, etc.) and such chains can be connected into immensely complicated directed networks (B is listed as a synonym of A, but A is not necessarily listed as a synonym of B). In "Synonym Chains" in the May 1988 Word Ways, I showed how chains could be constructed to connect antonyms, such as LIGHT-bright-cunning-furtive-sly-furtive-secret-hidden -obscure-DARK and DARK-obscure-vague-vacant-empty-foolish-simple-easy-LIGHT.
In this article, I focus instead on the syn groups. Certain ones have words in common; in the most extreme case, a set of sixteen have such an entanglement. These overlaps are diagrammed below. Selected adjectives in the same syn group are connected by 01, 02, 03, ... or 16; the full groups are listed at the end of this article. In addition, if one examines the synonyms in the main definition set of each word in a synonym group, one finds that 38 of these connect with other syn groups (labeled 21, 22, .... 37, 42); connections are indicated by < or >. The most notable of these is the word empty in the syn group VAIN-nugatory-otiose-idle-empty-hollow, which has the synonym foolish in the main definition set. This is part of the syn group SIMPLE-foolish-silly-fatuous-asinine, which in turn is linked with six other syn groups (40, 41.43, 44, 45, 46). Among the remaining syn groups, there is one linked group of five and two of four; most of the rest are isolated.
The word sensible is found in four different syn groups: AWARE-cognizant-conscious-sensible-alive-awake, MATERIAL-physical-corporeal-phenomenal-sensible-objective, PERCEPTIBLE-sensible-palpable-tangible-appreciable-ponderable, and WISE-sage-sapient-judicious-prudent-sensible-sane.
Why "Synonym Pudding"? I regard the syn groups as highly-connected subsets of synonyms, much like plums in a pudding; the other five-sixths of adjectives form the pudding filling.
Which two adjectives are farthest apart in the pudding? More precisely, each pair of adjectives can be connected by a minimum-length chain; for what pair is this minimum maximized? This extraordinarily-difficult question can only be answered with the aid of a computer. What do the corresponding synonym puddings for nouns or verbs look like?
21 foul < rank 03 musty > antiquated 22 02 > trite 23 02 24crude > ribald 04 vulgar 04 gross > ignorant 25 05 05 > individual 26 seeming 05 separate > detached 27 06 05 07 > autonomous 28 clear 08 apparent 08 plain 08 distinct 09 10 amenable 16 tractable > malleable 37 09 10 11 09 29 low < open 12 prone 12 liable 12 sensitive > delicate 30 09 10 13 09 frank supine 14 idle 14 inactive > lazy 31 transparent 10 15 > latent 32 candid > fair 33 otiose > futile 35 > blunt 36 15 34 empty > foolish 42 banal 46 flat 42 45 42 smooth 40 simple 40 easy 43 41 advisable 44 politic comfortable 02 FLAGRANT glaring gross rank 03 MALODOROUS stinking fetid noisome putrid rank fusty musty 04 COARSE obscene gross vulgar ribald 05 COMMON plain ordinary familiar plain vulgar 06 APPARENT illusory seeming ostensible 07 DISTINCT separate discrete 08 EVIDENT manifest patent distinct obvious apparent plain clear 09 CLEAR transparent translucent limpid 10 FRANK candid open plain 11 RESPONSIBLE answerable accountable amenable liable 12 LIABLE exposed open subject prone susceptible sensitive 13 PRONE supine prostrate recumbent 14 INACTIVE idle inert passive supine 15 VAIN nugatory otiose idle empty hollow 16 OBEDIENT docile tractable amenable 40 EASY facile simple light effortless smooth 41 COMFORTABLE cozy snug easy restful 42 SIMPLE foolish silly fatuous asinine 43 SUAVE urbane diplomatic bland smooth politic 44 EXPEDIENT politic advisable 45 LEVEL flat plain even smooth 46 INSIPID vapid flat jejune banal inane 21 DIRTY filthy foul nasty squalid 22 OLD ancient venerable antique antiquated archaic obsolete 23 TRITE hackneyed stereotyped threadbare 24 RUDE rough crude raw 25 IGNORANT illiterate unlettered untutored unlearned 26 SPECIAL especial specific particular individual 27 INDIFFERENT unconcerned incurious alone detached disinterested 28 FREE independent autonomous sovereign 29 BASE low vile 30 CHOICE exquisite elegant rare delicate dainty 31 LAZY indolent slothful 32 LATENT dormant quiescent potential 33 FAIR just equitable impartial unbiased dispassionate objective 34 DULL blunt obtuse 35 FUTILE vain fruitless 36 BLUFF brunt brusque curt crusty gruff 37 PLASTIC pliable pliant ductile malleable adaptable