stylus

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A sharp, pointed instrument used for writing, marking, or engraving.
• noun Computers A pointed instrument used as an input device on a pressure-sensitive screen.
• noun A phonograph needle.
• noun A sharp, pointed tool used for cutting the jagged grooves that record sound on a phonograph record.

from The Century Dictionary.

• noun A sponge-spicule of the monaxon uniradiate type, sharp at one end and not at the other. It is regarded as an oxea one of whose rays is suppressed.
• noun In entomology, a style or stylet.
• noun In a phonograph, a pointed part which rests on the diaphragm and is moved by the vibrations induced in the latter by sound-waves. It is used to produce the record of sounds upon the phonographic cylinders, and also to reproduce the sounds thus recorded.

from the GNU version of the Collaborative International Dictionary of English.

• noun An instrument for writing. See style, n., 1.
• noun That needle-shaped part at the tip of the playing arm of phonograph which sits in the groove of a phonograph record while it is turning, to detect the undulations in the phonograph groove and convert them into vibrations which are transmitted to a system (since 1920 electronic) which converts the signal into sound; also called needle. The stylus is frequently composed of a hard metal or of diamond.
• noun The needle-like device used to cut the grooves which record the sound on the original disc during recording of a phonograph record; it is moved by the vibrations given to the diaphragm by a sound, and produces the indented record.
• noun (Computers) A pen-shaped pointing device used to specify the cursor position on a graphics tablet.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A sharp stick used in ancient times for writing in clay tablets; a sharp tool for engraving.
• noun A phonograph needle.
• noun A small plastic stick used as a pen for writing on the touch sensitive screen of an electronic gadget.
• noun A tool for making small dots on a piece of heavy paper, used to produce Braille writing for the blind by hand.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a pointed tool for writing or drawing or engraving
• noun a sharp pointed device attached to the cartridge of a record player