What does consonance mean?

Consonant means "sounding together." As an adjective, it means "in agreement," "corresponding" or "harmonious." As a noun, a consonant is a sound that needs a vowel to "sound together" with in order to make a syllable.

Consonant is a speech sound that's not a vowel; a letter of the alphabet that represents a speech sound produced by a partial or complete obstruction of the air stream by a constriction of the speech organs.

Consonant letters in the English alphabet are B, C, D, F, G, H, J, K, L, M, N, P, Q, R, S, T, V, X, Z, and usually W and Y.