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 .}}

Adjective

(en adjective)

imposing]] or [[constitute, constituting a physical, mental, or figurative load which can be borne only with effort.

* 1820 , , "The Legend of Sleepy Hollow":

That all this might not be too onerous on the purses of his rustic patrons, who are apt to consider the costs of schooling a grievous burden, and schoolmasters as mere drones, he had various ways of rendering himself both useful and agreeable.

* 1848 , , Shirley , ch. 13:

Again, and more intensely than ever, she desired a fixed occupation,—no matter how onerous , how irksome.

* 1910 , , "The Golden Poppy" in Revolution and Other Essays :

[I]t has become an onerous duty, a wearisome and distasteful task.