means A salt-tolerant tree or shrub that grows in tidal coastal swamps, sending down tangled stilt-like roots that trap sediment and shelter wildlife.

from Likely from the Portuguese 'mangue' (itself probably borrowed from a Taíno or other Arawakan word of the Caribbean), later tangled up in English with 'grove' — the familiar word for a stand of trees — which reshaped the unfamiliar foreign term into something an English ear could hold. So a tropical name was quietly half-translated into 'mangrove,' as if the language itself reached out a root and grabbed the nearest solid thing.