Prime

The first hour of daylight; the first canonical hour.

The religious service appointed to this hour.

The early morning generally.

The earliest stage of something.

First in importance, degree, or rank.

"Our prime concern here is to keep the community safe."

First in time, order, or sequence.

"Both the English and French governments established prime meridians in their capitals."

First in excellence, quality, or value.

"This is a prime location for a bookstore."

(lay) Having exactly two integral factors: itself and unity (1 in the case of integers).

"Thirteen is a prime number."