abstruce -- Lucie

ab·struse  (b-strs, b-) adj. Difficult to understand; recondite. See Synonyms at ambiguous. [Latin abstrsus, past participle of abstrdere, to hide : abs-, ab-, away; see ab-1 + trdere, to push; seetreud- in Indo-European roots.] ab·strusely adv. ab·struseness n.

The American Heritage® Dictionary of the English Language.

Lucie is wise beyond her years and understands things that adults find abstruse.