styl-, stylo-, styli- +

(Greek: column; pillar; pillarlike implement or structure, especially the styloid process of the temporal bone)

stylus (s), styli (pl)
1. A pointed tool for writing, drawing, or engraving.
2. A pointed instrument used for engraving; especially, one used in ancient times for writing on clay or wax tablets.
3. The tracing pen on an electronic device such as a seismograph or polygraph that converts an electrical signal into a written record.
4. Etymology: "stem-like part of a flower pistil", alteration of Latin stilus "stake, stylus"; a spelling which was influenced by Greek stylos, "pillar".
A styliform process forming the posterior extremity of the vertebral column in some fish and tailess amphibians.