This is the 2916th most frequent Russian word.
волос
Hair (singular).
Here 'волос' is used to mean 'hair' in the singular form, referring to an individual's strand or collective condition.
Мой волос неожиданно стал очень ломким.
My hair has unexpectedly become very brittle.
In this context, 'волос' is used in the plural form 'волосы', referring to individual strands of hair found on the pillow.
На подушке я обнаружил несколько выпавших волос.
On the pillow, I found several fallen hairs.
Here, 'волос' is presented in the possessive form 'волосы', referring to the style or color of the hair overall in a poetic or descriptive sense.