An Etymological Dictionary of Astronomy and Astrophysics

The fainter of the two components in a → binary system.

Etymology (EN): Companion from O.Fr. compaignon “fellow, mate,” from
L.L. companionem, lit. “bread fellow, messmate,” from
L. → com- “with” + panis “bread.”

Etymology (PE): Hamdam “bearthing together, i.e. an intimate companion, friend,” from
ham- “with”, → com- + dam “breath,” Mod.Pers./Mid.Pers. damidan “to breathe, blow,” Av. dāδmainya- “blowing up,”
cp. Skt. dham- “to blow,” dhamati “he bows,” Proto-Indo-Iranian
*dhamH-, Proto-Iranian *damH- “to blow, breathe; to swell,” PIE
*dhemH- “to blow.”