Some time, sometime and sometimes.

According to the Oxford English Corpus, one of the changes in the English language is the increasing use of the single-word form of words that used to be commonly two-words such as "someday" or "sometime". This is also appears to be a particularly American phenomenon:

The phrase "some time" now appears as the fused single-word form "sometime" in 32% of all occurrences in American English and 19% of all occurrences in British English.

In American English someday has now become more or less standard, substantially outnumbering occurrences of some day; anymore and underway look set to follow. Although the same trend is apparent in British English, it tends to lag behind.

I personally still tend to write "some time" rather than "sometime". As a teacher of English, I also think it makes it easier for student to avoid the confusion between the adverbs:

• "some time" (as "at an indefinite time in the future")" Ex.: We'll meet some time/sometime next week.

• and "sometimes" (as "on certain occasions or in certain cases but not always") Ex.: Sometimes, I like watching a good game.

It can be very cinfusing for non-English speakers.

However, "some time" (in two words) can also mean "an appreciable length of time" as in: I've been waiting for some time, and in this case, I have yet to see it in one word, even in American English.