This straight up means ‘weird’. It has a negative context.
eg. 그 이상한 남자는 나한테 이거 줬어
That weird guy gave me this
I guess with the insinuation that he’s a little creepy or that there is no good reason for this weird guy to give me something
This also can translate to strange or weird, but it has more of the nuance of being cute or endearing. Something or someone that is 엉뚱하다 may be unpredictable. Kinda like they defy the rules of logic, but they’re strange in a endearing way. I’ve heard this word used to describe Lee Dong Wook’s character in Goblin
eg: 또깨비라는 드라마 있는 저승사자는 엉뚱해요
The Grim Reaper in the drama ‘Goblin’ is so funny
Tbh we don’t really have a word for this in English. So for this sentence you could use cute/odd/funny/strange in your translation but your tone would indicate the nuance of him also being cute and endearing and odd
This translates more to ‘unfamiliar’. So in English we could say that a place or person is strange if we haven’t been there/met them. (Of course, we tend to do this more in formal speech or in writing)
But yes, this translates more accurately to ‘unfamiliar’.
I’d give an example but idk any good ones rn and I don’t feel like thinking of any