The Collaborative International Dictionary of English v.0.48:
Somnial \Som"ni*al\, a. [L. somnialis dream bringing, fr. somnium dream, fr. somnus sleep.] Of or pertaining to sleep or dreams. [1913 Webster] The somnial magic superinduced on, without suspending, the active powers of the mind. --Coleridge. [1913 Webster]