Thaw
Old English thawian (verb), of West Germanic origin; related to Dutch dooien . The noun (first recorded in Middle English) developed its figurative use in the mid 19th century.
wiktionary
From Middle English thowen, thawen, from Old English þāwian, from Proto-West Germanic *þauwjan, from Proto-Germanic *þawjaną, from Proto-Indo-European *teh₂-(“to melt”).
etymonline
thaw (v.)
Old English þawian (transitive), from Proto-Germanic *thawon- (source also of Old Norse þeyja, Middle Low German doien, Dutch dooien, Old High German douwen, German tauen "to thaw"), from PIE root *ta- "to melt, dissolve" (source also of Sanskrit toyam "water," Ossetic thayun "to thaw," Welsh tawadd "molten," Doric Greek takein "to melt, waste, be consumed," Old Irish tam "pestilence," Latin tabes "a melting, wasting away, putrefaction," Old Church Slavonic tajati "to melt"). Intransitive sense from early 14c. Related: Thawed; thawing.
thaw (n.)
"the melting of ice or snow," also "spell of weather causing this," c. 1400, from thaw (v.). Figurative sense is from 1590s; specifically "relaxation of political harshness or hostility" from 1950, an image from the "Cold War."