DMnoun [ C ]
/ˌdiːˈem//ˌdiːˈem/informalabbreviation for direct message: a private message sent on a social media website, that only the person it is sent to can see:
She received threats and abuse in her DMs.
DMverb [ I or T ]
uk/ˌdiːˈem//ˌdiːˈem/informalabbreviation for direct message: to send someone a private message on a social media website:
I'm selling my bike. DM me if you're interested.