noun.
The early form of oak, preserved (through the shortening of the vowel before two consonants) in certain place-names (whence surnames): as, Acton [⟨ AS. Āctū n], literally, oak-town, or dwelling among the oaks: Acley or Ackley, also Oakley [⟨ AS. Ācleá], literally, oak-lea.
noun.
A prefix, assimilated form of ad- before c and q, as in accede, acquire, etc.; also an accommodated form of other prefixes, as in accurse, accloy, accumber, etc. See these words.
etc. Points of flexure in the heating curves of iron and steel. The point ac1 on heating is the same as ar1 on cooling, etc.
noun.
An adjective-suffix of Greek or Latin origin, as in cardiac, maniac, iliac, etc. It is always preceded by -i- and, like -ic, may take the additional suffix -al.