We don't have synonyms for man up yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are mat up, ran up and man u.
°to "be a man about it"; to do the things a good man is traditionally expected to do, such as: taking responsibility for the consequences of one's actions; displaying bravery or toughness in the face of adversity; providing for one's family, etc.
"I was wondering when he would man up and marry that girl he knocked up."
°(of military personnel in a unit) to assemble, each person manning (attending to) his station, prepared for departure of an aircraft, ship, etc.
°to "be a man about it"; to do the things a good man is traditionally expected to do, such as: taking responsibility for the consequences of one's actions; displaying bravery or toughness in the face of adversity; providing for one's family, etc.
"I was wondering when he would man up and marry that girl he knocked up."
°(of military personnel in a unit) to assemble, each person manning (attending to) his station, prepared for departure of an aircraft, ship, etc.