Meaning
Define <1,,3724, horizo>
(Eng., "horizon"), primarily means "to mark out the boundaries of a place" (as in the Sept. of Num 34:6, Jos 13:27); hence "to determine, appoint." In Heb 4:7, where the reference is to the time of God's invitation to enter into His rest, in contrast to Israel's failure to do so, the word may mean either the appointing of the day (i.e., the period), or the "defining" of the day, i.e., marking its limits. So the RV (AV, "limiteth"). See DECLARE, DETERMINE, LIMIT, ORDAIN.
