1924, from thermo- + sphere.
thermometer
thermonuclear
thermoplastic
Thermopylae
Thermos
thermosphere
thermostat
Theropoda
thesaurus
these
Theseus
)window.location='https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=byronic106@yahoo.com&lc=US&item_name=Donation+to +Help+Keep+Etymonline+Free+and+Open&no_note=0&cn=&curency_code=USD&bn=PP-DonationsBF:btn_donateCC_LG.gif:NonHosted'){kind=link}