There are a few words I recognize slightly, but repeatedly have to look up. The verb 'coruscate' and its adjective sibling 'coruscant' are such words.
George Eliot uses that word and I knew I should remember what it means, but I had to reach for the dictionary. Then I knew why I never remember this word -- because except when some silly writer uses it, I have no use for it.
Coruscate is a Latinate word and as Latin contributions go, I guess it's okay. It means to flash or flicker, like a fire. It has a bit of a crackling sound to it, which is good. But it doesn't come close to at least a half dozen or more Anglo-Saxon words that capture that feeling of a sparkling flame. Consider twinkle or glitter or shine. Sputter and shimmer. Glitter and glow; gutter and glimmer.
Who needs 'coruscate'? But I bet you and I won't have to look it up again!