A Sindarin word for “shipbuilder” or “shipwright”, most notably used as a name for Círdan of the same meaning (LotR/240; PE17/27). It was clearly a combination of cair “ship” [< ✶kiryā] and tân “builder, wright”. The Etymologies of the 1930s instead had N. cirdan “shipbuilder” with a short i (Ety/KIR), while the name was given as N. C(e)irdan [containing N. ceir “ship”] making its etymology clear (Ety/TAN). Cirdan’s name appeared with either a short i or long í in Lord of the Rings drafts of the 1940s (WR/76; SD/67).
Conceptual Development: The first version of the Tengwesta Qenderinwa (TQ1) of the 1930s had another word N. ciriaeth “shipwright” derived from ᴹ✶kirya-k’tō (PE18/62), but it was never used as a name.
Neo-Sindarin: For purposes of Neo-Sindarin, I think both círdan and ciriaeth can coexist, with the círdan referring to the principle designer or builder of the ship, and ciriaeth for other workers helping build the ship.
An Elf-lord who was a famous ship builder, whose name was translated “Shipwright” (LotR/240). His name is simply círdan “shipbuilder” used as a name (Ety/KIR).
Conceptual Development: In Lord of the Rings drafts from the 1940s, his name was first given as N. Cirdan with a short i (WR/76). His name appeared in The Etymologies as C(e)irdan (Ety/TAN), where the (e) probably indicates its development from N. ceir “ship” (later S. cair).