Well, it’s “abstract thing” as opposed to “concrete thing”, not abstract in the sense of giraffes and melting clocks.
One that amuses me a little is 怒る = おこる = to get angry. It’s composed of a woman (女) plus a heart (心) plus “again” (又, though that’s not really a kanji you’ll often find on its own), which quite readily lends itself to a(n albeit slightly stereotyped) mnemonic: “Yeesh, that woman is getting angry over matters of the heart again?”
As an added bonus, the components also hint at the reading: おんな + こころ + ~る = おこる