"exposure to the sun's rays," 1610s, from French insolation (16c.), from Latin insolationem (nominative insolatio), noun of action from past participle stem of insolare "place in the sun, expose to the sun," from in- "in" (from PIE root *en "in") + sol "sun" (from PIE root *sawel- "the sun").
insistence
insistent
insobriety
insociability
insolate
insolation
insole
insolence
insolent
insolubility
insoluble