Word Study
subtropics
OXFORD DICTIONARY
subtropics, n.pl. the regions adjacent to or bordering on the tropics.
Derivative
subtropical adj.
THESAURUS
subtropics
Antarctic Zone, Arctic Circle, Arctic Zone, Frigid Zones, Torrid Zone, Tropic of Cancer, Tropic of Capricorn, Variable Zones, climate, clime, equator, furnace, hell, horse latitudes, inferno, latitude, longitude, longitude in arc, meridian, oven, parallel, prime meridian, roaring forties, steam bath, the line, tropic, tropics, zoneFor further exploring for "subtropics" in Webster Dictionary Online