Answer: cyanic

AnswerCrossword Clue
CYANIC... acid.
CYANICPoisonous acid
CYANICBluish, as a flower
cyanica strong acid HOCN used to prepare cyanates
cyaniccontaining or pertaining to the cyano group
cyanicblue coloured
cyanicblue: applied esp. to a series of colors in flowers, including the blues and colors tending toward blue