AC

Multiple Entries:
  AC    Ac    -ac    ac-    actinium    ad-    alternating current  

Concise Oxford English Dictionary © 2008 Oxford University Press:
AC/eɪˈsiː/

▶abbreviation

• 1 (also ac) air conditioning.

• 2 Aircraftman.

• 3 (also ac) alternating current.

• 4 appellation contrôlée.

• 5 athletic club.

• 6 before Christ. [from L. ante Christum.]

• 7 Companion of the Order of Australia.

Concise Oxford English Dictionary © 2008 Oxford University Press:
Ac

▶symbol the chemical element actinium.

Concise Oxford English Dictionary © 2008 Oxford University Press:
-ac/ak/

▶suffix forming adjectives which are often also (or only) used as nouns, such as maniac. Compare with -acal.

– origin via L. -acus or Fr. -aque from Gk -akos.

Concise Oxford English Dictionary © 2008 Oxford University Press:
ac-/ak/

▶prefix variant spelling of ad- assimilated before c, k, and q (as in accept, acquit, and acquiesce).

Concise Oxford English Dictionary © 2008 Oxford University Press:
actinium /akˈtɪnɪəm/

▶noun the chemical element of atomic number 89, a rare radioactive metallic element of the actinide series that occurs as an impurity in uranium ores. (Symbol: Ac)

– origin early 20th cent.: from Gk aktis, aktin- ‘ray’ + -ium.

Concise Oxford English Dictionary © 2008 Oxford University Press:
ad- /ad/ (also a- before sc, sp, st; ac- before c, k, q; af- before f; ag- before g; al- before l; an- before n; ap- before p; ar- before r; as- before s; at- before t)

▶prefix

• 1 denoting motion or direction to: advance.

• 2 denoting reduction or change into: adulterate.

• 3 denoting addition or increase: adjunct.

– origin from L. ad ‘to’.

Concise Oxford English Dictionary © 2008 Oxford University Press:
alternating current (abbrev.: AC)

▶noun an electric current that reverses its direction many times a second at regular intervals. Compare with direct current.