root hair

WordReference Random House Unabridged Dictionary of American English © 2025

root′ hair′, 

1. Botany an elongated tubular extension of an epidermal cell of a root, serving to absorb water and minerals from the soil.

• 1855–60

Collins Concise English Dictionary © HarperCollins Publishers::

root hair noun

1. any of the hollow hairlike outgrowths of the outer cells of a root, just behind the tip, that absorb water and salts from the soil