is it correct to say "look upward" or "look upwards?"

what is the difference between upwards and upward?


Thanks

 

"Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.

upward (adv., adj.), upwards (adv.)

Upward is the adjective, as in He took an upward swing with the bat. Upwards is the more common adverb, but upward too is an adverb, as in We climbed upwards [upward] along the ridge. All three are Standard."

 

Thanks so much Starfrown! But then, when needing to use the adverb, how does one choose between them?

 

I know that I use both as adverbs, so it may simply boil down to which I happen to prefer at a given moment. As far as I know, there's no true rule.

The situation is the same with other similar words:

toward/towards
backward/backwards
homeward/homewards

 

Thanks Starfrown!