Of keen penetration or discernment; cunning; sagacious.Synonyms Sagacious, Sage, Knowing, Astute, Subtle. Sagacious and sage are used only in good senses, and when applied to persons generally suggest the wisdom of age or experience. The knowing man has wide knowledge and often penetration. The word knowing has also a humorous cast: as, he gave me a knowing wink; it may be used ironically: as, he is a little too knowing, that is, he thinks he knows more than he does; it may be used of knowing more than one has a right to know; it sometimes suggests a disposition to make ill use of knowledge: as, a knowing leer. Astute is often the same as sagacious, but is susceptible of an unfavorable sense in the direction of a narrow shrewdness, slyness, or cunning; it often means a sagacity that knows how to be silent; it is frequently applied to looks. Subtle, in its good sense, implies great acuteness, delicacy, or refinement in mental action: as, a subtle reasoner. For its bad sense, see cunning.