Webster’s Revised Unabridged Dictionary · 1913
Didactic
Di·dac′tic, Di·dac′tic·al, a. [Gr. διδακτικός, fr. διδάσκειν to teach; akin to L. docere to teach: cf. F. didactique. See Docile.] Fitted or intended to teach; conveying instruction; preceptive; instructive; teaching some moral lesson; as, didactic essays. "Didactical writings." Jer. Taylor.
The finest didactic poem in any language. Macaulay.
Di·dac′tic, n. A treatise on teaching or education. [Obs.] Milton.