unvoiced

adjectives

produced without vibration of the vocal cords
"unvoiced consonants such as `p' and `k' and `s'"
hard, surd, unvoiced, voiceless
antonym
voiced
not made explicit
"the unexpressed terms of the agreement"; "things left unsaid"; "some kind of unspoken agreement"; "his action is clear but his reason remains unstated"
unexpressed, unsaid, unspoken, unstated, unuttered, unverbalised, unverbalized, unvoiced