C14: from Latin extendere to stretch out, from tendere to stretch
Word Origin and History for extends
extend
v.
early 14c., "to value, assess;" late 14c. "to stretch out, lengthen," from Anglo-French estendre (late 13c.), Old French estendre "stretch out, extend, increase," from Latin extendere "stretch out," from ex- "out" (see ex-) + tendere "to stretch" (see tenet). Related: Extended; extending.
extends in Medicine
extend ex·tend (ĭk-stěnd') v.ex·tend·ed, ex·tend·ing, ex·tends To straighten a limb; unbend.