稀疏,稀少 sparse, by New E-C, means few and scattered.
稀罕 rare--不足,缺乏 scarce
A dictionary defines 稀少 as scarce, by A Practical C-E, this item is not compatible with English countpart.
稀疏 稀少 sparse population , sparse hair, are not 不足,缺乏,稀罕
不足缺乏 Water being scarce is not Water being 稀疏.
By W N D S:
"sparse"
---meager,spare, exiguous, scanty, skimpty, *Ana: scattered, dispersed, sporatic, occasional,infrequent,uncommon, thin, slim, slender, *Ant dense * Con close, thick, compact.
"scarce"
---rare, uncommon,infrequent,occasional, sporatic, *Ana deficient, curtailed *Ant abundant
Based on this, scarce and sparse, at most cases, should not translated to the same character.
scarce has no contrasted word.
rare's contrasted word is common, common's con. is 稀罕.
We say he is a genius, not say that the common people as "nongenius", instead we use "common".
