I doubt there are many editors who would reject work featuring one or more of the following minor bloopers. But I see them a lot. Curiously, I also see inconsistency in close proximity – “every day I get up and everyday I have breakfast” – which always makes me wonder whether the writers must have thought it better to hedge a guaranteed one out of two than risk an evens-odds zero. Or perhaps they think either option is acceptable, or that it matters not a jot. Maybe they just don’t notice.
Okay. If this doesn’t come to you instinctively, one way of deciding is to use a synonym. I have a niggling feeling the method may not be full-proof, but that I can’t think of an obvious exception suggests to me that it will do, at least to be going on with.
Anyone / any one
The synonym to resolve this is ‘anybody’, which is the same as ‘anyone’.
If you can substitute the one-word ‘anybody’, then use the one-word ‘anyone’. If you can’t, then use the two-worded ‘any one’.
* “Is anyone going?” is correct, because so is “Is anybody going?”
* “Is anyone of you going?” is incorrect, because so is “Is anybody of you going?”
* So, “Is any one of you going?” is correct.
Anyway / any way
The synonyms here are ‘regardless’ or ‘nevertheless’ or, perhaps better, ‘anyhow’, which are each more or less ‘anyway’.
If you can substitute one of these single words, then use ‘anyway’. If you can’t, then use ‘any way’.
* “What happened to you, anyway?” is correct, because so is “What happened to you, anyhow?”
* “Is there anyway of knowing?” is incorrect, because so is “Is there anyhow of knowing?”
* So, “Is there any way of knowing?” is what you need.
(You can also think of ‘any way’ as being the same as ‘any manner’ or ‘any means’.)
You get the picture, so moving more swiftly through some others…
Everyday / every day
‘Everyday’ means ‘commonplace’ or ‘ordinary’.
‘Every day’ means ‘each day’.
Do a substitution to see which you need.
Everyone / every one
Same logic as anyone / any one.
Forever / for ever
‘Forever’ means ‘continually’ (eg ‘I am forever losing my keys’).
‘For ever’ means ‘for always’ (although ‘forever’ seems to be increasingly accepted too).
Maybe / may be
‘Maybe’ means ‘perhaps’.
‘May be’ roughly means ‘might be’.
Sometime / some time
‘Sometime’ means ‘occasional’ (eg ‘Her sometime partner’)
‘Some time’ means ‘a period of time’ (eg ‘I will call some time later’)
There are bigger mistakes than these when you’re starting out – probably each of the twenty-two preceding this one – but if you care about words – and you’re a writer, so you do – then it’s a shame to not try to get it right.
A seemingly reliable rule of thumb, then: if you can replace it with a word, it’s a word. If you can only replace it with two (or more) words, it’s two words.