The onocentaur has the upper body of a man and the lower body of an onager (wild ass). The upper part is rational; the lower part is exceedingly wild.

See also the centaur.

The onocentaur is a symbol of male lust. The two-part nature of the beast symbolizes the hypocrite who speaks of doing good but actually does evil; Philippe de Thaon says that man is rightly called man when he is truthful, but an ass when he does evil.

The onocentaur and the siren are often illustrated together because they both symbolize the sin of lust.