1. the smallest angle of incidence for which light is totally reflected;
The Collaborative International Dictionary of English v.0.48:
Critical \Crit"ic*al\ (kr[i^]t"[i^]*kal), a. [See Critic, n.,
1. Qualified to criticise, or pass judgment upon, literary or
It is submitted to the judgment of more critical
ears to direct and determine what is graceful and
what is not. --Holder.
2. Pertaining to criticism or the critic's art; of the nature
of a criticism; accurate; as, critical knowledge; a
3. Inclined to make nice distinctions, or to exercise careful
judgment and selection; exact; nicely judicious.
Virgil was so critical in the rites of religion,
that he would never have brought in such prayers as
these, if they had not been agreeable to the Roman
4. Inclined to criticise or find fault; fastidious; captious;
O gentle lady, do not put me to 't,
For I am nothing, if not critical. --Shak.
5. Characterized by thoroughness and a reference to
principles, as becomes a critic; as, a critical analysis
of a subject.
6. [See Crisis.] Pertaining to, or indicating, a crisis,
turning point, or specially important juncture; important
as regards consequences; hence, of doubtful issue;
attended with risk; dangerous; as, the critical stage of a
fever; a critical situation.
Our circumstances are indeed critical. --Burke.
The small moment, the exact point, the critical
minute, on which every good work so much depends.
Critical angle (Optics), that angle of incidence of a
luminous ray at which it is wholly reflected, and no
portion of it transmitted. The sine of this angle is the
reciprocal of the refractive index of the medium.
Critical philosophy, the metaphysical system of Kant; -- so
called from his most important work, the "Critique of Pure
WordNet (r) 3.0 (2006):
n 1: the smallest angle of incidence for which light is totally