Vowel harmony
Compound words do not undergo vowel harmony in their constituent words as in "bugün" ('today'; from "bu", 'this', and "gün", 'day') and "başkent" ('capital'; from "baş", 'prime', and "kent", 'city') unless it is specifically derived that way. Vowel harmony does not usually apply to loanword roots and some invariant suffixes, such as and "-ken" ('while ...-ing'). In the suffix "-e"2"bil" ('may' or 'can'), only the first vowel undergoes vowel harmony. The suffix "-ki" ('belonging to ...') is mostly invariant, except in the words "bugünkü" ('today's') and "dünkü" ('yesterday's').