(he eschate hemera): Repeatedly used by Jesus in Jn (6:39,40,44,54; 11:24; 12:48) for the day of resurrection and judgment (see ESCHATOLOGY OF THE NEW TESTAMENT). Compare the usage in the Old Testament (Isa 2:2; Mic 4:1) and the New Testament (Ac 2:17; 2Ti 3:1; 2Pe 3:3; 1Jo 2:18; Jude 1:18) of "last days" and "last time" to denote the Messianic age.
In Joh 7:37, "the last day, the great day of the feast" refers to the eighth day of the feast of Tabernacles. This closing day was observed as a Sabbath (Le 23:36). On it the libation of water made on other days was not made; hence, the allusion of Jesus to Himself as the Giver of the living water.