From The Collaborative International Dictionary of English v.0.48:
Alight \A*light"\, v. i. [imp. & p. p. Alightedsometimes Alit; p. pr. & vb. n. Alighting.] [OE. alihten, fr. AS. [=a]l[imac]htan; pref. [=a]- (cf. Goth. us-, G. er-, orig. meaning out) + l[imac]htan, to alight, orig. to render light, to remove a burden from, fr. l[imac]ht, leoht, light. See Light, v. i.] 1. To spring down, get down, or descend, as from on horseback or from a carriage; to dismount. [1913 Webster]
2. To descend and settle, lodge, rest, or stop; as, a flying bird alights on a tree; snow alights on a roof. [1913 Webster]
3. To come or chance (upon). [R.] [1913 Webster]
From The Collaborative International Dictionary of English v.0.48:
Alight \A*light"\, a. [Pref. a- + light.] Lighted; lighted up; in a flame. "The lamps were alight." --Dickens. [1913 Webster]