Where does "wicked" get its /ɪd/ from?

Question

There are three ways I know to pronounce the -ed at the end of an adjective:

1. /t/ as in cracked.
2. /d/ as in lined.
3. /ɪd/ as in naked

I realise naked is a special case because, as etymonline states, it comes for Old English nacod, so the suffix isn't added.

This answer shows the pattern of pronunciation of -ed in all other cases. However it doesn't explain why wicked ends with /ɪd/ (or /id/ or /əd/ depending on the dialect).

Etymonline says that wicked comes from OE wicca, so the d wasn't already there.

Why do we pronounce wicked as /ˈwɪkɪd/ and not /ˈwɪkt/?

Answer 1

According to A Critical Pronouncing Dictionary and Expositor of the English Language, 1839,

The adjectives naked, wicked, picked (pointed), booked, crooked, forked, tusked, tressed, and wretched, are not derived from verbs, and are therefore pronounced in two syllables. The same may be observed of scabbed, crabbed, chubbed, stubbed, shagged, snagged, ragged, scrubbed, dogged, rugged, scragged, hawked, jagged; to which we may add, the solemn pronunciation of stiff-necked; and these when formed into nouns with the addition of ness, preserved the ed in a distinct syllable, as wickedness, scabbedness, raggedness, &c.

This explanation is reaffirmed in the book, Teaching Pronunciation: A Reference for Teachers of English to Speakers of Other Languages, 1996,

Whether they function as verbs or adjectives, most English words ending in the -ed suffix follow the same phonological rules as the paste tense inflectional ending (e.g., striped /t/, forked /t/, cultured /d/, used /d/, moneyed /d/, furrowed /d/, good-natured /d/, gray-haired /d/, blue-eyed /d/). There are, however, historically based differences in pronunciation between certain formed ending in -ed, depending on whether they function as adjectives or verbs. The -ed adjectives in this category have an extra syllable and take the /ɪd/ pronunciation, whereas the verbs simply take /t/ or /d/, following the rules for the regular past tense and regular past participle outlined earlier:

[Table with examples comparing the pronunciation of verb forms of words such as blessed, beloved, learned, dogged, and legged, with their adjectival equivalents]

Sometimes, even when there is an adjective with no corresponding verb, the adjective is still pronounced /ɪd/ (naked, wretched, rugged, wicked).

Answer 2

OK, here's my two-cents worth.

(1) There are actually three ways of pronouncing the -ed endings: <ɪd> (near-close front vowel, commonly occurring in urban U.S. dialects), <əd> (unstressed mid-central vowel, commonly occurring in rural North Midland dialects), and (mid-vowel sound, now rare in America but still prominent in many British dialects).

Wicked is pronounced with two syllables because it refers to an animate thing (usually human). Thus it is like legged (a two-legged beast), hanged (a hanged person), naked (a naked person), etc. There are other words which do not belong in this category, as modern English is a very messy language. For example, wretched. But note that wretched originally applied only to humans and was applied to nonhumans over time.

Back to wicked: wicked (wɪkt) is applied to inanimate things/nonhumans, such as a lamp, just as legged (legd) is applied to inanimate things/nonhumans, such as a table. Whether the word ends in a t or a d is determined by the position of the tongue just before the final consonant, just like whether we pronounce an s or a z sound in plural forms.

The interesting question for linguists is how wicked attained its present form, given that it is derived from a substantive form, not a verbal form—probably by analogy with other adjectival verbs, just like modern American English snuck was formed by analogy with cling, clung, clung. Originally it was sneak, sneaked, sneaked.

There are other words in this category too. /lɜrnd/, as in 'I learned something' v. /'lɜr nɪd/, as in 'a learnèd man'. /bɜnt/, as in 'a bent leg of a chair', v. /'bɜn dɪd/, as in 'a man on bended knee'.