n. [ L. acumen, fr. acuere to sharpen. Cf. Acute. ] Quickness of perception or discernment; penetration of mind; the faculty of nice discrimination. Selden. [ 1913 Webster ]
[ひじちょうもく, hijichoumoku](exp) sharp eyes and ears used for collecting information far and wide; having the acumen and shrewd discernment gained by widely-collected information; being well-versed on a subject; books which broaden our knowledge[Add to Longdo]