You raise a good point, but in this case annexum is the perfect passive participle of third conjugation verb annectere, "to tie, bind to, connect." The English word "annex" came from late Latin through Old French (the roots of the French elements of English are found in the Battle of Hastings, won by the Normans). According to the following Wiki entry, the Greek word is a French loan: https://el.wiktionary.org/wiki/ανεξάρτητος The French, of course, derives from Latin. This modern Gk word does not precede the French-Latin word. Regarding the influence of French on modern Greek, see examples from Peter Mackridge, The Modern Greek Reader, 314-22. Another example of a French word with a Latin root used in Modern Gk is η βιτρίνα "shop window" // Fr vitre from Latin vitrum. Have a lingot.