The word "searing" comes from the verb sear, which derives from Old English searian, meaning "to dry up" or "wither", linked to a Proto-Germanic root, saurajan (source of dryness), explaining senses like "wind-seared".  The meaning evolved to "brand" or "burn" (c. 1400) and then to cooking (scorching meat) and intense feelings/criticism (like "searing pain") in later centuries, with the adjective searing appearing in the mid-1600s. 

The term "searing" (as a noun) was first used in English in the Middle English period (1150-1500), with the earliest evidence in the Oxford English Dictionary (OED) dating from 1395.  Other forms of the word have different initial usage dates:
"Sear, v." (verb, meaning to dry up, wither, or burn) has evidence from the Old English period (pre-1150). 
"Seared, adj." (adjective) first appeared in a dictionary by Thomas Elyot in 1538. 
"Searing, adj." (adjective, meaning extremely hot or powerful and critical) is first evidenced from 1665 in the writing of Richard Brathwait. 

Examples of "searing" used in a sentence: 
"She felt a searing pain in her foot." 
"She made a searing attack on her political enemies."
"The adobo has a mild kick to it, but not a searing heat." 
"I winced from the searing sting of pain through my neck." 
"He deftly finds her lips and bends her in a long, searing kiss." 
"Both goals came from searing crosses to the back side of the goal." 
"He could feel a searing pain in his head and his vision was blurred."
"There was no shade, so I couldn't get away from the searing heat of the sun" 

Just the facts:

SEARING Definition & Meaning - Merriam-Webster

SEARING Synonyms: 211 Similar and Opposite Words | Merriam-Webster Thesaurus