Crosswords Solver

Answer: apophony
Answer	Crossword Clue
apophony	(in Indo-European languages) regular alternation in the internal phonological structure of a word element, esp. alternation of a vowel, that is coordinated with a change in grammatical function or combination, as in English sing, sang, sung, song;
apophony	a change in root vowels of verb forms

Crossword

a puzzle consisting of a grid of squares and blanks into which words crossing vertically and horizontally are written according to clues.

Answer: apophony