alpha privative(n = noun.communication) - the negative prefix a- or un-;
is a kind of prefix

alpha, alpha and omega, alpha blocker, alpha brass, alpha bronze, alpha centauri, alpha crucis, alpha decay, alpha fetoprotein, alpha foetoprotein, alpha geminorum, alpha globulin, alpha iron, alpha methyl dopa, alpha orionis, alpha paper, alpha particle, alpha radiation, alpha ray, alpha rays, alpha receptor, alpha rhythm, alpha software, alpha test, alpha wave, privative