IPA: //ˌkɒdɪˈsɪləri//
KK: /kɒdɪˈsɪlɛri/
Relating to a document that adds to or modifies a will.
The lawyer explained the codicillary changes made to the original will.
Codicillary → It is formed from "codex" (from Latin *codex*, meaning a book or manuscript) and the suffix "-ary" (meaning pertaining to or connected with). The word "codicillary" refers to something that is related to or characteristic of a codex or manuscript.
Think of a 'codex' as a type of book or manuscript, and remember that 'codicillary' means something related to that kind of book.
No commonly confused words.