There may be all sorts of reasons for my not knowing a word. It might be really old and not have been in use for a while. It may be slang that I don’t recognize. Or it may be part of a specialized branch of knowledge that I know nothing about.
The latter is my excuse for not knowing “dehiscence” when I came across it in H. G. Wells’s The Food of the Gods. In the context of the novel it’s clear that it refers to the bursting open of pollen sacs and that’s what I figured it’s only meaning was. On looking into it, however, I found it’s also a fairly common bit of medical terminology, referring to the rupture or splitting open of a suture or surgical wound. I suppose if you’re a medical professional you’d know this one right away (and maybe not know its botanical meaning), but I’ll confess I pulled a complete blank on it. Seems like the kind of word that could get plugged into a lot of other contexts though, so I’m going to keep it filed away.