'To explain away' definitions:

Definition of 'To explain away'

From: GCIDE

Explain \Ex*plain"\ ([e^]ks*pl[=a]n"), v. t. [imp. & p. p. Explained([e^]ks*pl[=a]nd"); p. pr. & vb. n. Explaining.] [L. explandare to flatten, spread out, explain; ex out + plandare to make level or plain, planus plain: cf. OF. esplaner, explaner. See Plain,a., and cf. Esplanade.]
1. To flatten; to spread out; to unfold; to expand. [Obs.] [1913 Webster]
The horse-chestnut is . . . ready to explain its leaf. --Evelyn. [1913 Webster]
2. To make plain, manifest, or intelligible; to clear of obscurity; to expound; to unfold and illustrate the meaning of; as, to explain a chapter of the Bible. [1913 Webster]
Commentators to explain the difficult passages to you. --Gay. [1913 Webster]
To explain away, to get rid of by explanation. "Those explain the meaning quite away." --Pope.
Syn: To expound; interpret; elucidate; clear up. [1913 Webster]