Boyd’s Bible Dictionary:
Five Hebrew words are rendered vale or valley in the Bible, only one of which seems to imply that broad sweep of land between mountains or hills generally understood by valley
The others imply (1) a narrow ravine, gorge, or glen (Deut. 34:3,6); (2) a wady, dry in summer but a torrent in rainy weather; (3) a plain (Josh. 11:8,17; 13:17; 2 Chron. 35:22; Zech. 12:11); (4) a stretch of sloping ground (Deut. 1:7; Josh. 10:40; 1 Kings 10:27; 2 Chron. 1:15; Jer. 33:13).
Concise Bible Dictionary:
There are few places in Palestine which resemble the valleys of other countries. Two of the words translated “valley” are also translated “plain,” and signify broad plains between the hills. Two other words refer to the narrow dales or ravines through which the streams run in winter, but many of which are dry in summer, now called wadys.
The words are
1. biqah, “valley or plain,” which is the word used for the valleys or plains of Aven, Jericho, Lebanon, Megiddo, Mizpeh, and Ono.
2. erneq, “valley or plain,” more resembles an English “valley”: it is applied to Achor, Ajalon, Baca, Berachah, Beth-aram, “of decision” (Joel 3:14); Elah; of the giants (Josh. 15:8; Josh. 18:16); Gibeon, Hebron, Jehoshaphat, Jezreel, Keziz, “of the King,” or “the King’s Dale” (Gen. 14:17; 2 Sam. 18:18); Rephaim, Shaveh, Siddim, and Succoth.
3. gay, ge, ravine, narrow glen: applied to Charashim, Hamon-Gog, Hinnom, Son of Hinnom, Jiphthah-el, Zeboim, and Zephathah; and used symbolically for “Valley of the Mountains” (Zech. 14:5); “of the passengers” (Ezek. 39:11); “of salt” (2 Sam. 8:13; 2 Kings 14:7; 1 Chron. 18:12; 2 Chron. 25:11; Psa. 60 title); “of craftsmen” (Neh. 11:35); “of slaughter” (Jer. 7:32; Jer. 19:6); “of vision” (Isa. 22:1,5); “of the shadow of death” (Psa. 23:4).
4. nachal, gorge, wady, often translated “brook” and “river”: the valleys are Eshcol, Gerar, Shittim, Sorek, Zared.
5. shephelah, translated “vale” and “valley,” but not specified by any proper name. It refers to the lowlands that lie midway between the highlands and the low plains of Judah. See CANAAN.
6. φάραγξ. “Every valley shall be filled, and every mountain and hill shall be brought low” (Luke 3:5): a quotation from Isaiah 40:4, where the Hebrew word is gay.
Valley in Sinai