'beside' vs 'besides'

[ilovepsycho]

Q. We need to discover another source of income, beside oil

Is that sentence not correct gramatically or in terms of standard English?
I'd appreciate it if you tell me why.

[nativeSpeaker]

I'm a native English speaker and I have a BA in English. I would say that the sentence is not grammatical. The word should be "besides," not "beside." "Besides" and "beside" are two different lexical entries in the dictionary. "Besides" means "other than" (which is appropriate for this sentence) and "beside" means "next to." That said, I just looked up "beside" in the Merriam Webster dictionary and it has "besides" as its second definition (confusing). Personally, I have never heard anyone use "beside" as you have used it here, and I would not consider the words interchangeable. (So, use "besides" instead.)

Hope this helps.