Englishfor English speakers
Ac
—
noun
(= actinium)
a radioactive element of the actinide series; found in uranium ores
AC
—
noun
an electric current that reverses direction sinusoidally
In the US most household current is AC at 60 cycles per second
concept
Noun
—
A concept is an idea.
Italy has introduced the concept of "parental leave" - time off work given to either parent to look after the child.