Abbreviations
The Latin abbreviations a.m. and p.m. (often written "am" and "pm", "AM" and "PM", or "A.M." and "P.M.") are used in English, Portuguese and Spanish. The equivalents in Greek are π.µ. and µ.µ., respectively.
Most other languages lack formal abbreviations for "before noon" and "after noon", and their users use the 12-hour clock only orally and informally. However, in some languages, such as Russian and Hebrew, non-formal designations are used, such as "9 in the morning" or "3 in the night".
In practice, when abbreviations and phrases are omitted, one relies on sentence context and common sense to distinguish the meaning. For example, if one schedules an appointment with a doctor at "9:00" on a certain date, that means 9:00 a.m.; but if a social dance is scheduled to begin at "9:00", it means 9:00 p.m.
Read more about this topic: 12-hour Clock