monstrous

Etymology

From Middle English monstrous, from Old French monstrueuse, monstrüos, from Latin mōnstrōsus. Compare monstruous.

adj

1. Hideous or frightful.
2. Enormously large.
   a monstrous height
   Possibly monster pumpkins may become still more monstrous by the shoots being ringed, and so may other vegetables and fruits where quality is of less importance than mere size. December 20, 1901, “The Ringing of Plants”, in The Agricultural Journal and Mining Record, volume 4, number 21, page 663
3. Freakish or grotesque.
   He, therefore, that refuses to do good to them whom he is bound to love […] is unnatural and monstrous in his affections. 1650, Jeremy Taylor, The rule and exercises of holy living
4. Of, or relating to a mythical monster; full of monsters.
5. (obsolete) Marvellous; exceedingly strange; fantastical.