In Leviticus 18, from verse 6 then on, there is a big chunk of passages about not "uncovering the nakedness" of relatives...or is it about not "having sexual relations with" them?
This link provides various translations:
Biblical Hermeneutics Stack Exchange is a question and answer site for professors, theologians, and those interested in exegetical analysis of biblical texts. It only takes a minute to sign up.Sign up to join this community
The Hebrew formulation is:
עֶרְוַ֥ת אֲחֽוֹת־אִמְּךָ֖ לֹ֣א תְגַלֵּ֑ה כִּֽי־שְׁאֵ֥ר אִמְּךָ֖ הִֽוא׃ (Lev 18:13, Westminster Leningrad Codex)
Literally, the term גילוי עריות means "uncovering nakedness". However, this is just a euphemism for sexual relations.
Note, however, that since Hebrew does not have explicit terms for sexual relations, all mentions of such actions use euphemisms of various sorts.