Hard and soft declensions
'Hard' consonants are d, t, g, h, k, n, r. 'Ambivalent' labials b, p, m, v, liquid l, and sibilants s, z mostly count as 'hard', but not always
'Soft' consonants are ď, c, ť, ň, ř (diacritic letters), č and j (but c is occasionally 'hard')
Hard nouns regularly end in a 'hard' or 'ambivalent' consonant, -a, or -o
Soft nouns regularly end in a 'soft' consonant, -e, -ost or -í