Tevul Yom is a tractate in the Mishnah and Tosefta; in most editions of the Mishnah, it is tenth in the order Tohorot.
According to Leviticus 15:5 et seq., one who takes the prescribed ritual immersion remains impure until sunset.
The degree of impurity in such a case is slight, and according to rabbinical interpretation, such a person renders neither the dough offering nor sanctified flesh is unclean, even before sunset; it is merely rendered unfit (pasul).
He may touch profane or unsanctified things without consequence.
This tractate precisely defines the degree of impurity attaching to such a person, and stipulates how far the purity of anything is affected by his touch.