Maithun (मैथुन) means sexual intercourse or sexual union. In Jainism, this is a conduct topic linked to moral discipline:

• For laypersons (householders), sex is allowed within marriage, but it should be governed by restraint and ethical conduct.
• For Jain monks and nuns, celibacy is strictly observed; maithun is forbidden.

There are no major differences in the basic meaning between Digambar and Shwetambar traditions; the key point is the same: maithun relates to sexual activity and its appropriate or prohibited contexts in Jain ethics.