Answer: auxin

AnswerCrossword Clue
AUXINComputer speaker abbr.
AUXINPort term on many stereos
auxinany of various usually acidic organic substances that promote cell elongation in plant shoots and usually regulate other growth processes (as root initiation) as
auxinclass of substances that in minute amounts regulate or modify the growth of plants, esp. root formation, bud growth, and fruit and leaf drop
auxinant hormone
auxina growth promoting substance