Some of the processes that derive adjectives from verbs straddle the divide between derivation and inflection in a way that we have not yet encountered. We met the suffixes -ed, -en and -ing, and vowel change, in passive and progressive participle forms of verbs. However, such forms (in italics in (23)) can also be adjectives:

(23) a. a not very interesting book

        b. The party-goers sounded very drunk.

        c. The car seemed more damaged than the lamp-post.

The modifier very and the comparative construction (more … than) show that interesting, drunk and damaged are adjectives here, not forms of the verb lexemes INTEREST, DRINK and DAMAGE. (Notice that very cannot modify verbs, so one cannot say *That book very interested me.) As for drunk, its status as belonging to a distinct lexeme here is confirmed by its special meaning (‘intoxicated through drinking alcohol’), not predictable from the meaning of the verb DRINK (‘swallow liquid’).

Further suffixes that commonly form adjectives from verbs, with their basic meanings, are:

(24) -able ‘able to be Xed’: breakable, readable, reliable, watchable

(25) -ent, -ant ‘tending to X’: repellent, expectant, conversant

(26) -ive ‘tending to X’: repulsive, explosive, speculative

Expectations derived from these basic meanings can, as usual in derivation, be overridden; for example, CONVERSANT does not mean ‘tending to converse’. We have already encountered -able in (22), where the variant, or allomorph, -ible is also illustrated. What is striking about the -ible words in (22) is that their bases, although they have clearly identifiable verbal meanings such as ‘eat’, ‘read’ and ‘touch’, are bound rather than free. Some of these bound verb roots appear in a number of derived lexemes, such as the aud- root that occurs in (IN)AUDIBLE, AUDITION, AUDIENCE and AUDITORY.

Suffixes that form adjectives from nouns are more numerous. Here are some:

(27) -ful, e.g. joyful, hopeful, helpful, meaningful

(28) -less, e.g. joyless, hopeless, helpless, meaningless

(29) -al, e.g. original, normal, personal, national

(30) -ish, e.g. boyish, loutish, waspish, selfish

As will be seen, adjectives in -ful and -less tend to come in pairs, although the correspondence is not exact: we have SLOTHFUL but not ‘SLUTHLESS’, and PENNILESS but not ‘PENNIFUL’. This confirms again that, even when the meaning of a potential word may be easily guessable (a ‘slothless’ person would be hardworking, and a ‘penniful’ person would be well off ), the existence of the word is not guaranteed.