malaltaĵo, malaltejo angolul

lowland [lowlands]▼(area which is lower than surroundings)
noun
[UK: ˈləʊ.lənd] [US: ˈloʊ.lənd]

valley▼(elongated depression between hills or mountains)
noun
[UK: ˈvæ.li] [US: ˈvæ.li]