a. Physics. [f. Gr. ἀ priv. + θερμαν- stem of θερμαίν-ειν to heat (f. θέρμη heat) + -OUS.] Not permeable by radiant heat.
1863. Tyndall, Heat, iii. 79. An athermanous body which stops the radiation.
1871. B. Stewart, Heat, § 206. This substance is … athermanous, that is to say opaque for heat.
