any of several plant hormones, including gibberellic acid, whose main action is to cause elongation of the stem: used in promoting the growth of plants, in the malting of barley, etc
gibberellin in American English
(ˌdʒɪbərˈɛlɪn)
noun
one of a group of organic compounds, secreted by an ascomycetous fungus (Gibberella fujikuroi), which behave like plant hormones in stimulating seed germination, growth of roots, leaves, and stems, etc.
Word origin
< ModL Gibberella (dim. of L gibber, hump on the back < gibbus: see gib1) + -in1