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.
The white, half-moon shape at the base of your nail is called the lunula. It is a visible part of the nail matrix where new nail cells are produced.
When there is no moon visible in the sky, it is called a new moon. During this phase, the side of the moon facing Earth is not illuminated by the sun.
Phases of the moon
The moon is called a new moon when it is not visible on Earth due to its position in relation to the Sun.
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.
The white, half-moon shape at the base of your nail is called the lunula. It is a visible part of the nail matrix where new nail cells are produced.
When there is no moon visible in the sky, it is called a new moon. During this phase, the side of the moon facing Earth is not illuminated by the sun.
Phases of the moon
The moon is called a new moon when it is not visible on Earth due to its position in relation to the Sun.
When the moon is visible during the day, it is called a "day moon." This occurrence happens because of the moon's position in its orbit around Earth where it can be seen from Earth in daylight hours.
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
When the moon is fully visible to observers on Earth, it is called a full moon. This occurs when the sun, Earth, and moon are aligned with the Earth in the middle, causing the moon to be fully illuminated by the sun.
You can tell if the moon is increasing or decreasing in light by observing its shape in the sky. During a waxing moon, it will appear to be growing larger, while during a waning moon, it will appear to be shrinking. Additionally, a waxing moon will be visible in the evening, while a waning moon will be visible in the morning.
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.
The first visible thin slice of the moon is called a waxing crescent. It occurs when the illuminated portion of the moon is increasing but less than half.