| Ac |
symbol of the chemical element actinium. |
| accidental |
in music, a symbol that indicates that a note should be played or sung one or two semitones higher or lower than is otherwise indicated. In most cases, the pitch is to be raised or lowered by one half step, as from F natural to F sharp. [1/5 definitions] |
| actinium |
a radioactive chemical element of the rare-earth group that has eighty-nine protons in each nucleus. (symbol: Ac) |
| Ag |
symbol of the chemical element silver. |
| Agnus Dei |
a lamb as a symbol of Jesus Christ; Lamb of God. [1/2 definitions] |
| Al |
symbol of the chemical element aluminum. |
| aluminum |
a chemical element that has thirteen protons in each nucleus, occurs commonly in ores such as bauxite, and in pure form is a strong lightweight corrosion-resistant silvery metal with many industrial uses. (symbol: Al) |
| Am |
symbol of the chemical element americium. |
| americium |
a synthetic radioactive chemical element that has ninety-five protons in each nucleus. (symbol: Am) |
| antimony |
a chemical element that has fifty-one protons in each nucleus and forms a brittle bluish white metal crystal, used in hard alloys, electrical components, and medicines. (symbol: Sb) |
| Ar |
symbol of the chemical element argon. |
| argon |
a chemical element of the inert gas group that has eighteen protons in each nucleus. (symbol: Ar) |
| armband |
a cloth band worn around the upper arm as a badge of rank, membership, or the like, or as a symbol, as of mourning. |
| arrow |
a symbol shaped like an arrow, used to show position or direction. [1/3 definitions] |
| arsenic |
a poisonous chemical element that has thirty-three protons in each nucleus and occurs in brittle, grayish white crystalline masses or in yellow or black allotropes. (symbol: As) [1/2 definitions] |
| As |
symbol of the chemical element arsenic. |
| astatine |
a highly radioactive chemical element of the halogen group that has eighty-five protons in each nucleus. (symbol: At) |
| At |
symbol of the chemical element astatine. |
| Au |
symbol of the chemical element gold. |
| B |
symbol of the chemical element boron. |
| Ba |
symbol of the chemical element barium. |