Clipping
The loss of tonal information when values are pushed past the maximum or minimum a file can encode.
In depth
Clipping happens per channel, so a red flower can clip its red channel while green and blue still hold detail, producing a flat, plastic-looking patch of colour. Because the camera's rear-screen histogram is built from an embedded JPEG, the raw file usually holds between a half and a full stop more headroom than the display suggests.
Examples in practice
Deep red rose petals in sunlight clip the red channel and lose all vein texture while the leaves beside them are perfectly exposed.