Kalmar "homothermic" tana nufin iyawar kwayoyin halitta don kula da yanayin zafi na cikin gida dawwama, ba tare da yanayin zafi na waje ba. A wasu kalmomi, yana nufin iyawar dabba don daidaita yanayin jikin ta da kuma kiyaye ta a cikin kunkuntar kewayo, wanda ya zama dole don aiki mai kyau na matakai daban-daban na ilimin lissafi. Wannan kuma ana kiransa da "jinin-dumi." Dabbobin homothermic sun hada da tsuntsaye da dabbobi masu shayarwa, sabanin dabbobi masu rarrafe kamar dabbobi masu rarrafe da masu rarrafe, wadanda suka dogara da yanayin waje don daidaita yanayin jikinsu.