But sometimes, just sometimes, dictionaries can be flipping annoying.
Take this genuine dictionary definition of tepal, for instance: any of the subdivisions of a perianth that is not clearly differentiated into calyx and corolla.
Anyone out there any further forward?
delta particle: a very short-lived hyperon.
(To make things even worse, a hyperon is defined as any baryon that is not a nucleon.)
Really, what do these dictionary people think they're about?
Well, there's a phrase to describe exactly what they're about, that is, giving an explanation that requires so much expert knowledge that anyone who could understand it wouldn't need to look it up in the first place.
It's ignotum per ignotius.
It's Latin for, more or less, come off it!
Phrase To Have Ready To Use If People (especially teachers) Start Using Too Many Unknown Words: ignotum per ignotius. This phrase is Latin for the unknown by means of the more unknown.
The teacher here is Humphry Davy.