verified etymologyen
entertain
inter
among, between
tenēre
to hold
to hold among — to hold together
To entertain is to hold each other in the middle. The oldest English sense is ‘to keep up, to maintain, to keep someone in a frame of mind’; ‘amuse’ is a later drift. To entertain someone was first to keep them near.
source · Old French entretenir < Latin inter ‘among’ + tenēre ‘to hold’ — etymonline.com/word/entertain