бейек • (beyek)
from Old Turkic bedük "big, large", from Old Turkic verbal stem bedü- "to grow large", from Proto-Turkic *bEdü- (“to grow large”).
See also the Etymology section at бөйөк (böyök).
Cognate with Kazakh биік (bïik), Kyrgyz, Southern Altai бийик (bïyïk, “tall”), etc.