Easton's Bible Dictionary (1897)
An eminence, natural or artificial, where worship by sacrifice or offerings was made (1 Kings 13:32; 2 Kings 17:29). The first altar after the Flood was built on a mountain (Gen. 8:20). Abraham also built an altar on a mountain (12:7, 8). It was on a mountain in Gilead that Laban and Jacob offered sacrifices (31:54).
After the Israelites entered the Promised Land they were strictly enjoined to overthrow the high places of the Canaanites (Ex. 34:13; Deut. 7:5; 12:2, 3), and they were forbidden to worship the Lord on high places (Deut. 12:11-14), and were enjoined to use but one altar for sacrifices (Lev. 17:3, 4; Deut. 12; 16:21). The injunction against high places was, however, very imperfectly obeyed, and we find again and again mention made of them (2 Kings 14:4; 15:4, 35:2 Chr. 15:17, etc.).