Disillusion - dissolution

Except in careful speech, these are homophones, and so a writer in a hurry can confuse them. (The careful speaker will voice the second ‘ si ’ in disillusion, with the same sound as in ‘confusion’ IPA: /ʒ/. The ‘ ti ’ in dissolution is unvoiced, like the sound in ‘attention’ IPA: /ʃ/.) It may help you to distinguish them to note their etymology.

• To disillusion is a verb meaning ‘to take the illusion away from’. It is built from the prefix dis- , which has one ‘ s ’, and the noun illusion, which does not start with ‘ s ’. So disillusion has only one ‘ s ’ in its first syllable. (The related noun is disillusionment.)

• dissolution is a noun from the verb to dissolve. That in turn is built from dis (one ‘ s ’) and solve, which starts with ‘ s ’. So dissolution has two ‘ s ’s in the first syllable.