What does "Full Cowling" mean? Cowling: the removable cover of a vehicle or aircraft engine.
So when Deku uses One for All-Full "Cowling" (as spelled in subs), does it refer to him removing the limiter on his power, or is it just mispronounciation ? Shouldn't it be "calling" instead?
By using Full Cowl, Mydoria effectively uses All For One power on whole his body, rather than focusing on specific part.

This is most probably why this skill was called "Full Cowl". But it is not clear if author explicitly decided to use word "cowl", or rather didn't knew difference between it and some other english words with similar meaning (e.g. "coverage").