«والغرابة: كون الكلمة غير ظاهرة المعنى»
Gharābah means that a word's intended meaning is not readily apparent.
An expression may be so rare in ordinary usage that its sense must be recovered from specialized lexical evidence. A listener then cannot readily identify the intended meaning from the word alone.
This is a semantic problem. It should be distinguished from the articulation problem of sound discord and the formal problem of morphological irregularity.