n. (Chem.), A plant growth hormone of the gibberellin series (C19H22O6), also called gibberellin A₃. It was first isolated from the fungus Gibberella fujikuroi. It is used to promote the growth of seedlings. See also gibberellin. MI11 [ PJC ]

n. (Chem.), Any of a number plant growth hormones, the first of which was isolated in 1938 from the fungus Gibberella fujikuroi; more than 60 related gibberelins are known. The most important is gibberellin A₃, also called gibberellic acid. They are used in agriculture for promoting plant growth. [ WordNet 1.5 +PJC ]