hair: the strands that grow on the head, face, or body of a person or animal, taken together as a whole head or coat of hair, and by extension the coarse hair woven into a rough garment
This is the ordinary word for hair. It is a collective noun, so a single form names the whole growth at once, the way English can say a person has thick "hair" without counting the strands. One word covers the hair of the head, the beard, and the rest of the body, and it works the same way for the shaggy coat of an animal.
Most of its appearances are plainly physical. Priests inspect the hair inside a patch of diseased skin to see whether it has turned white or yellow, a Nazirite lets his hair grow untouched and then shaves it, Samson's strength returns as his hair grows back, and a poet compares a woman's flowing hair to a flock of goats streaming down a hillside. In a few places the same word names hair as raw material: a rough cloak woven from animal hair, the recognizable dress of a prophet.
Because the word is so plain, the only places a reader can trip are a couple of set expressions built on it. Scripture can speak of "the hair of the feet" as a modest way of naming hair on the lower body, and a "garment of hair" is a coarse woven cloak, not the wearer's own long locks.