A slate or enamel board for writing on with chalk; a predecessor to a whiteboard.
To write or draw on a chalkboard.
A thin, flat, circular plate or similar object.
A disc - either a CD-ROM, an audio CD, a DVD or similar removable storage medium.
A ring- or cup-shaped enlargement of the flower receptacle or ovary that bears nectar or, less commonly, the stamens.
Something resembling a disk.
A type of harrow.
An intervertebral disc
To harrow.
To move towards, or operate at, zero blade pitch, orienting the propeller blades face-on to the oncoming airstream and maximising the drag generated by the propeller.