understanding, comprehension / appreciation

difficult / hard, probably impossible

understand, comprehend / appreciate

(chemistry) a benzene ring with two substituents in alternate positions / (chemistry) an oxyacid with relatively few water molecules

meta-

(cant, jargon) German silver

(slang) meta

(chiefly women's speech) first person singular pronoun: I, me

(polite) first-person singular pronoun: I, me

a personal or private matter / (by extension) selfishness