Entertaiment is an art form that uses external stimuli to evoke emotions in the viewer. It can be anything from television to a concert. Entertainment often hits on points that the human mind was evolved to deeply react to, eg social backstabbing or murders. This can stimulate the brain to realease seratonin, dopamine and other chemicals.
Entertainment is also the name of a magazine.
From Middle English entretenement, from Old French entretenir, from inter- “among” + tenir, from Latin tenere, from PIE root *ten- “to stretch.” Sense of “to gratify, amuse” is 1620s; that of “provide for” is early 17c.
A common suffix of Latin origin forming nouns from verb stems (amazement, betterment, merriment). It is inserted with the prefix -e- when the stem ends in -er, as in commence-e-ment and send-i-ment; it is inserted with the suffix -ment on verb stems ending in -ir, as in fright-i-ment and astonish-i-ment.