(computing, formal) megabyte (1,000 kilobytes or 1,000,000 bytes). / (computing, informal) mebibyte (2¹⁰ (1024) kibibytes or 2²⁰ (1,048,576) bytes).

(China, slang) moneyboy. / (computing) Motherboard. / (military, US) Initialism of marine barracks. / (Thailand) million baht. / Bachelor of Medicine degree (Latin: Medicinae Baccalaureus).

Manitoba, a province of Canada. / Initialism of Myers–Briggs. / Initialism of Mercedes-Benz. / Initialism of Matchbox.

(knitting) Abbreviation of make bobble.

(Internet slang, text messaging) Initialism of my bad.

(Internet slang, text messaging) Abbreviation of maybe.

(computing, formal) megabit (1000 kilobits or 1,000,000 bits) / (computing, informal) mebibit (1024 kibibits or 1024² bits)

Alternative letter-case form of MB (“my bad”)

Alternative letter-case form of MB (“maybe”)

plural of MB