Used other than figuratively or idiomatically: see first, night.
The first night after marriage.
The first public performance of a play or other show, normally assumed to be held in the evening.
The beginning of something.
The proximal end of attachment of a muscle to a bone that will not be moved by the action of that muscle.
An arbitrary point on Earth's surface, chosen as the zero for a system of coordinates.
The source of a river, information, goods, etc.
Ancestry.
The point at which the axes of a coordinate system intersect.