Chemistry

Mas is:
- the "holy bread" eaten by members of the Armenian Apostolic Church at the end of the Divine Liturgy; not to be confused with communion and not etymologically related to "the Mass".
- an abbreviation for masquerade, a part of carnival tradition from Trinidad and Tobago where characters such as "Pitchy Patchy" (Jonkonou) and "Dame Lorraine" are depicted.
- a nickname for Massimo

MAS is a three-letter acronym for the following:
- multi-agent system
- Mozilla Application Suite
- mass air sensor
- Manufacture d'Armes de Saint-Étienne ("weapon manufacture of Saint-Étienne", French supplier of weaponry, thus the MAS acronym in several firearms used by the Military of France, including the FAMAS; now part of GIAT Industries)
- Melbourne Anime Society
- Monetary Authority Of Singapore, Singapore's central bank.
- Muerte a Secuestradores , a Colombian paramilitary group.

Mas