Verbs derived from nouns and from adjectives are numerous. Some affixes for deriving verbs from nouns are:

(38) de-, e.g. debug, deforest, delouse

(39) -ize, e.g. organize, patronize, terrorize

(40) -(i)fy, e.g. beautify, gentrify, petrify

There are also some common verbs that are derived by replacing the final voiceless consonant of a noun with a voiced one, perhaps with some vowel change too (parallel to the relationship between BELIEF and BELIEVE, although there it was the verb that seemed more basic):

(41) Nouns                   Verbs

        BATH                     BATHE

        BREATH                 BREATHE

        HOUSE […S]          HOUSE […Z]

        WREATH               WREATHE

A meaning for de- at (38) is clearly identifiable, namely ‘remove X from’ (compare its function in deriving verbs from verbs, e.g. DESENSITISE). However, neither -ise nor -ify has a clearcut meaning apart from its verb-forming function (ORGANISE does not share any obvious element of meaning with ORGAN, for example). The suffixes -ise and -ify can derive verbs from adjectival bases too, as in NATIONALISE, TENDERISE, INTENSIFY, PURIFY. Hence, when the roots to which they are attached are bound (e.g. CAUTERISE, SANITISE, PETRIFY, SATISFY, MAGNIFY), it is often impossible to decide whether these roots are fundamentally nominal or adjectival. The suffix -ATE shows the same sort of ambivalence. Words such as GENERATE, ROTATE, REPLICATE and LOCATE clearly contain a root and a suffix, because the same roots crop up elsewhere (e.g. in GENERAL, ROTOR, REPLICA, LOCAL). However, because most of the bases to which -ate is attached are bound roots, it does not clearly favor either adjectival or nominal bases.

It will be evident by now that suffixes play a larger role than prefixes in English derivational morphology. But there is still one prefix to be mentioned: en- (with its allomorph em-), which forms verbs meaning ‘cause to become X’ or ‘cause to possess or enter X’ from a few adjectives and nouns: ENFEEBLE, ENSLAVE, EMPOWER, ENRAGE, ENTHRONE, ENTOMB.

With the adjectives BOLD and LIVE as bases, the prefix en- is combined with a suffix -en: EMBOLDEN, ENLIVEN. This suffix usually occurs without the prefix, however, and does so quite widely (e.g. TIGHTEN, LOOSEN, STIFFEN, WEAKEN, WIDEN, REDDEN, DEEPEN, TOUGHEN). These verbs have either an intransitive meaning, ‘become X’, or a transitive one, ‘cause to become X’. The adjectives that can constitute bases for such verbs share an unusual characteristic, however, which becomes evident when we consider some verbs in -en that are imaginable, yet do not occur: *GREENEN, *NARROWEN, *STRONGEN, *TALLEN, *BLUEN, *CLEAREN. It turns out that the adjectives that can be bases for deriving -en verbs are all monosyllabic and all end in plosives (the sounds usually spelled p, b, t, d, (c)k and g in English) or fricatives (including the sounds usually spelled s, th, f and v). What is wrong with *GREENEN and the other unsuccessful candidates is that their bases end in a sound other than a plosive or a fricative – although with STRONG we get round this restriction (so to speak) by adding -en instead to the corresponding noun, STRENGTH (which ends in a fricative sound), so as to yield STRENGTHEN.

Can we then say that all adjectives ending in a plosive or a fricative, or at least a systematically identifiable subset of these adjectives, can be the base for a verb in -en? That is a question about productivity. However, the starting-point for an answer is to look for adjectives which end in plosives or fricatives but for which there is no corresponding verb in -en.