dog-leg, dogleg, or dog leg?

I've asked How does one dogleg from Florida to a sun-synchronous orbit? in Space Exploration SE about the path that a rocket takes during launch, or actually the ground-track of its path.

If the rocket launching from Florida were to go into a polar orbit, it would have to do some kind of dogleg maneuver. I'm still waiting to see exactly what this means.

If I look in Wikipedia's Dogleg disambiguation page, I see three spellings now see two spellings; dog-leg, dogleg. I'm pretty sure I've seen "dog leg" in other places as well. I'm using dogleg in the following:

A dogleg maneuver is when a satellite doglegs, executing one dogleg after another, following along a doglegged or dogleg-shaped path...

but can I just use any spelling I want, or are there preferred ways to do this?

Solution 1:

There is a common historical pattern in English with adjective-noun or noun-noun pairs that become set phrases. First, a noun is used as a modifier of another noun, for example . Then as this becomes a set phrase, the pronunciation shifts the stress from the modified noun backwards to the modifier which has lost a lot of its significance as a modifier and is turning from somewhat of a prefix to an integral part of a full word. At this point in spelling the pair gets a hyphen. Then eventually, they can be written as a single word.

Sometimes the middle hyphenated stage is skipped, sometimes spelling is altered. And sometimes it gets stuck in one stage.

For the pair 'dog' and 'leg', it seems that the online dictionaries are all over the place.

• M-W 'dogleg' with no mention of 'dog leg'
• Collins 'dog leg' or 'dogleg' or 'dog-leg
• Cambridge 'dogleg (also dog-leg)'.

Google NGrams seems to consider 'dogleg' much more popular in American English, and in UK English 'dogleg' is only recently slightly more common that 'dog leg'.

It should be noted that:

• many dictionaries (online and paper) treat word pairs differently than hyphenated or single words (sometime not at all). So a dictionary may not consider 'dog leg' as a possible entry at all.
• many online dictionaries search engines convert the hyphen to a space (implicitly making it two words rather than a single word).
• Google search for 'definition dog leg' will give all variants because Google is like that.

Solution 2:

If you look closely at the ODO (Oxford Dictionary Online), they claim that dogleg is American English, while dog-leg is British English. They could have made this clearer, but if you're maintaining an on-line dictionary, it's hard to get everything right.

If you look at Google Ngrams, this is more or less true, although both versions of English use both forms. And the one-word form is catching up with the hyphenated form in British English. I suspect it will eventually become dominant in both places¹

The two-word form isn't at all common in either AmE or BrE – I don't see any reason to use it.

¹ This is a fairly standard evolution for hyphenated words in English; for example, to-day and to-morrow used to be hyphenated.