Adjective

(en adjective)

hideous or frightful

* Shakespeare

So bad a death argues a monstrous life.

enormously large

a monstrous height

a monstrous ox

freakish or grotesque

* John Locke

a monstrous birth

* Jeremy Taylor

He, therefore, that refuses to do good to them whom he is bound to love is unnatural and monstrous in his affections.

of, or relating to a mythical monster; full of monsters

* Milton

Where thou, perhaps, under the whelming tide / Visitest the bottom of the monstrous world.

(obsolete) marvellous; strange

Adjective

(en adjective)

causing fear, dread, awe or admiration as a result of size, strength, or some other impressive quality; commanding respect; causing wonder or astonishment

difficult to defeat or overcome

* {{quote-news

, year=2012 , date=May 9 , author=John Percy , title=Birmingham City 2 Blackpool 2 (2-3 on agg): match report , work=the Telegraph citation , page= , passage=Holloway has unfinished business in the Premier League after relegation last year and he will make a swift return if he can overcome West Ham a week on Saturday. Sam Allardyce, the West Ham manager, will be acutely aware that when the stakes are high, Blackpool are simply formidable .}}