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Webster 1913 Edition

Adj.

[

Plano-

convex

Plane or flat on one side, and convex on the other;

as, a

plano-convex

lens

. See

, and

Adj.

[plain and convex.] Plain or flat on one side and convex on the other; as a plano-convex lens.

See also: planoconvex

plano-convex ‎(comparative more plano-convex, superlative most plano-convex)

Flat or plane on one side and rounded on the other, such that the center is thicker than the edges.

plano-convex in The Century Dictionary, The Century Co., New York, 1911
plano-convex in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913