Why is the ninth month called September?
late 15c., "to keep up, maintain, to keep (someone) in a certain frame of mind," from Middle French entretenir (12c.), from Old French entretenir "hold together, stick together, support," from entre- "among" (from Latin inter; see inter-) + tenir "to hold" (from Latin tenere; see tenet).
Sense of "have a guest" is late 15c.; that of "amuse" is 1620s. Meaning "to allow (something) to consideration" (of opinions, notions, etc.) is 1610s. Related: Entertained; entertaining.
Entertainments, "feasts," were sometimes connected with a public festival (Deut. 16:11, 14), and accompanied by offerings (1 Sam. 9:13), in token of alliances (Gen. 26:30); sometimes in connection with domestic or social events, as at the weaning of children (Gen. 21:8), at weddings (Gen. 29:22; John 2:1), on birth-days (Matt. 14:6), at the time of sheep-shearing (2 Sam. 13:23), and of vintage (Judg. 9:27), and at funerals (2 Sam. 3:35; Jer. 16:7). The guests were invited by servants (Prov. 9:3; Matt. 22:3), who assigned them their respective places (1 Sam. 9:22; Luke 14:8; Mark 12:39). Like portions were sent by the master to each guest (1 Sam. 1:4; 2 Sam. 6:19), except when special honour was intended, when the portion was increased (Gen. 43:34). The Israelites were forbidden to attend heathenish sacrificial entertainments (Ex. 34:15), because these were in honour of false gods, and because at such feast they would be liable to partake of unclean flesh (1 Cor. 10:28). In the entertainments common in apostolic times among the Gentiles were frequent "revellings," against which Christians were warned (Rom. 13:13; Gal. 5:21; 1 Pet. 4:3). (See BANQUET.)