Try re-wording your phrase a little bit, please, so we can properly answer your question.
The general term for the visible lit part of the moon is "the phase of the moon." The visible lit portion can have a crescent shape, a gibbous shape or a "half-moon" (half circle) shape.
Phases of the moon
still called a moon
the moon is the black shadow
An eclipse
The general term for the visible lit part of the moon is "the phase of the moon." The visible lit portion can have a crescent shape, a gibbous shape or a "half-moon" (half circle) shape.
Phases of the moon
still called a moon
the moon is the black shadow
An eclipse
A new moon is when there is little of the moon visible, except possibly a thin crescent. A full moon is when all of the moon is visible.
Full Moon
Full Moon
The different shapes are called phases.New MoonFirst QuarterFull MoonLast QuarterNew MoonphasesNew moon [not visible], waxing crescent [growing crescent shape], first quarter [right half is visible], waxing gibbous [growing from half to full], full moon [complete circle], waning gibbous [shrinking from full to half], third quarter [left half visible] and waning crescent [shrinking crescent shape].Moon PhasesPhases
The moon does not really change shape- its visible outline changes. This is due to the angle of sunlight falling on the moon in relation to the earth. If the sunlight is shining at a 90 degree angle from one side, then half the moon is illuminated and visible, half is dark.
It is called a new moon.
Each month the moon goes through phases from new moon to full moon. The last visible slice before a new moon is called a waning crescent.