es·trous adjective oroes·trous\ˈestrəs, chiefly Brit ˈēs-\; alsoes·traloroes·tral\-rəl\; ores·tru·aloroes·tru·al\-rəwəl\ Etymology: New Latin estrus, oestrus + English -ous or -al 1.: of, relating to, or characteristic of estrus < the estrous state > < estrous keratinization of the vaginal mucosa > 2.: exhibiting estrus : being in heat < the estrous bitch >