it is now usual to say 'íllustrate'.

Adjectives of this class take as early a stress as they can, as
'órnate', 'pínnate', 'délicate', 'fórtunate'. Nouns from all these
words throw the accent back and shorten or obscure all but the
penultimate vowel, as 'ignorance', 'evaporation'.

STEMS IN -IA. Here even disyllables shorten the penultima, as 'copy',
'province', while longer words throw the stress back as well as
shorten the penultima, as 'injury', 'colony', while 'ignominy' almost
lost its penultimate vowel, and therefore threw back the stress to the
first syllable. Shakespeare frankly writes the word as a trisyllable,

Thy ignomy sleep with thee in the grave.

Milton restored the lost syllable, often eliding the final vowel, as
in

Exile, or ignominy, or bonds, or pain.

Even with heavy consonants we have the early stress, as in 'industry'.
Greek words follow the same rules, as 'agony', 'melody'. Some words
of this class have under French influence been further abbreviated, as
'concord'.

Corresponding STEMS IN -IO keep the same rules. Perhaps the only
disyllable is 'study'; the shortening of a stressed _u_ shows its
immediate derivation from the old French _estudie_. Trisyllabic
examples are 'colloquy', 'ministry', 'perjury'. Many words of this
class have been further abbreviated in their passage through French.