Holding house of water
Kahālāwai reads as the house that holds water, and it is accurate: this older, eroded range catches enormous rainfall and feeds the streams that made west and central Maui farmable.
The English name, the West Maui Mountains, describes a location. The Hawaiian name describes a function.
Older than Haleakalā
The range is the remnant of a volcano much older than Haleakalā, cut into deep valleys — ʻĪao among them. Its summit is Puʻu Kukui.