I am not usually surprised by French pronunciation anymore at this point, but every now and then I still stumble into something I realize I didn't know.
Today I heard a native speaker use the word aspect, pronounced in a way that to me sounded like aspé, and I was surprised. Presumably if it was spelled aspecte the ct would not be silent? Is ect always silent at the end of a word? What about ict, uct, oct, act?
Narrowing it to -ect word final for the moment, some words ending in -ect are pronounced with the [ɛ] ending. Your mileage may vary literally on regional aspects for some, the onset of the following word, and of course register (theatre, poetry, conversation, and what sound comes next in any given elocution). A big one for [kt] is correct which may also end in [k].
Here's a group that usually ends in a vowel sound [ɛ] (see note on -spect below):
Contrast with these which often end in [kt]:
And some can go either way:
Parts of speech and meaning matter.
Notable "exception" is correct, which does pronounce the /ɛkt/ (or [k] regionally), but not ending in a vowel sound. A theory on the pronunciation from the Latin etymology comes from the Latin past participle correctus.
Au XVIIe s. il y a hésitation au plur. et devant consonne du mot suiv. entre [εkt], [εk], [εt] et [ε]. La prononc. expressive en [-kt] devait l'emporter.
Many words that end in the vowel already lost the c spelling and [k] in some parts of speech or meaning but retain it in other inflections: objet, objectif, effet, effectuer.
There are about seven words that end in -spect, root spec from Latin (specto, spectare, spectavi, spectatus and speciō, specere, spexi, spectum). Only one does not end in [ɛ], anspect, a technical and rare word, exceptional to this root from a bit of a fluke, it alone ends in [k].
PRONONC. : [ɑ̃spek]. Passy 1914 est le seul dict. à ne pas transcrire la finale [k] : ɑ̃:spε. Mart. Comment prononce 1913, p. 216 fait observer : ,,il ne faut pas assimiler aux autres mots en -spect le mot technique anspec(t), terme de marine, qui n'a pris un t dans l'orthographe que par une fausse analogie avec les autres : c'est le seul mot où le c doive toujours se prononcer, et toujours seul.`` Accord également des dict. du xixes. pour la finale [k].
Otherwise, a mnemonic for words that do not pronounce the word final [kt] coda would be the root -spect: aspect, circonspect, irrespect, prospect, respect, and suspect all end in [ɛ].
Words in -act are always pronounced /akt/
Artefact, contact, exact, impact, intact, tract
Words in -ict are pronounced /ikt/, except the rare amict (/a.mi/), that I didn't know before researching this topic.
Addict, district, strict, verdict
Words in -inct are pronounced /ɛ̃/ (-ct is silent)
distinct*, instinct, succinct
It's worth noting that the feminine succincte is /syk.sɛ̃t/ (the c is silent). For all the other words in -ct, the feminine -cte is pronounced /kt/ as expected.
For words in -ect, it depends. As mentioned by Livresque, words in -ect pronounced /ɛ/ usually lost their c, but some have resisted that change. These are pronounced /ɛ/:
Aspect, circonspect, prospect, respect, suspect
While these are pronounced /ɛkt/:
Abject, affect, correct, direct, infect, intellect, select (anglicism)
There are no words ending in -uct or -oct in French.
* For distinct, the pronunciation /distɛ̃kt/ can also be found sometimes.
