In dictionaries I looked at, it says “some time” is used when talking about an unspecified long time. Is it wrong to use it when talking about, say, a few minutes? For instance, let’s say someone stared at me for 10 seconds. Can I say, “He stared at me some time and then came and said hi.”
Can I say "He stared at me some time and then came and said hi" when the time was only ten seconds?
No, I would not use "some time" in that case. As you found when you looked up the phrase, "some time" means a long amount of time relative to the expected or usual duration—so if you are talking about a computer CPU, for example, and it waits or hangs for ten seconds, saying that it hangs "for some time" could be appropriate. If someone took ten seconds to walk across a crowded room you would not say it took them "some time" because you do not expect them to do it much faster than that.
As Andy mentions in the comments, "some time" is usually found in a prepositional phrase with "for:" "He stared at me for some time." Compare this with a while, which can be used without a preposition, and in fact is written as awhile when it is.
Can I say, “He stared at me some time and then came and said hi.”
Yes, in my honest opinion you can (just with the alteration of "stared at me for some time)
Some time to me always implies an unspecified amount of time (e.g. some time passed before he went back home.) The beauty of the way 'some time' can be used is that it's up to the reader to decide what they would consider 'some'. In this case, even if you take in account the dictionary definition of 'some time', staring at someone for 10 seconds straight sure as hell feels like a long time.
Let's take a different example; "John waited for some time for his train to arrive."
In this case I'd imagine the reader to picture something more than a couple of minutes, because if that's what you meant, you'd say it.
To conclude, in a lot of sentences I think 'a short while' would probably flow better. Because it conveys the message of the time span being shorter.
If we're talking about spoken language I would say no for a couple of reasons.
“He stared at me some time and then came and said hi.” Can be easily heard as “He stared at me sometime and then came and said hi.”
Sometime would then refer to a singular event in the past, in which case, it might initially be interpreted as a claim that, in one singular instance, at some point in the past this person stared at you then came over and said hi. If that interpretation didn't fit the context the listener would then have to mentally backtrack for the alternate interpretation where the person stared at you for a bit (of time) then came over and said hi.
You might have picked up on it from that last sentence but the easy way to resolve that ambiguity would be to say: “He stared at me for some time and then came and said hi.”
Even then, as other commenters have pointed out "[for] some time" generally refers to a relatively long period of time, so the larger context would determine if "[for] some time" is warranted. You'd have to setup some pretty specific context for it to work though.
Off the cuff example of when staring for 10 seconds, then saying "hi" could warrant a "[for] some time":
- "I awoke, confused and cotton mouthed, in a small brightly lit room. In the corner of the room crouched a man, looking for all the world as if he had been plucked from some college campus. We locked eyes. I tried to speak but my mouth would not yet work. He stared at me for some time and then came and said hi. His name was Derrick, and he wanted to know what was going on."
- "New hair, new dress, new eyeliner. Total makeover. He was going to be at the party. I never had the courage to speak to him, tell him how I feel. I wasn't even sure he knew I existed. Maybe today that would change. I pushed through the crowded house to the patio and there he was, and there I was. He stared at me for some time and then came and said hi."
In general though, without some reason for 10 seconds to be a long experience "[for] some time" would feel out of place.
Yup I can agree with whatever people above say. Sometime is relative.
After walking for some time, I reach the school.
After some time, I decided to walk to John and have a conversation with him.
For 1, it can range to minutes to a few. Whereas for 2, it can be just a few seconds. However, so far, I have not seen a case where people put sometime in a range of days to months. And yes if there is no grammar mistake, I think you could say that.