The bay north of Dol Amroth in early maps of Gondor from the 1940s (TI/312, WR/434), unnamed in the maps published in The Lord of the Rings. The name is similar to N. hobas “harbourage” and ᴱQ. kópas “harbour”. It was probably derived from the root ᴹ√KOP, a (rejected) variant of ᴹ√KHOP > hobas from The Etymologies of the 1930s (Ety/KOP, Ety/KHOP). See the entry on ᴹ√KHOP for details.
Noldorin
cirban
noun. [ship] haven
cirban
noun. haven
cobas
place name. Haven
hûb
noun. haven, harbour, small land-locked bay
lorn
noun. haven
A noun appearing as N. cirban “haven” in The Etymologies of the 1930s as a combination of N. ceir “ship” [vs. S. cair] and N. pann “courtyard” (Ety/PAN), so more literally “✱ship-enclosure”.
Neo-Sindarin: Some Neo-Sindarin writers instead use ᴺS. círbann as suggested in HSD (HSD), with the long í inspired by S. círdan (as opposed to N. cirdan), and long final -nn in disyllables being a common convention in Neo-Sindarin of the 2000s, as suggested by Helge Fauskanger. Personally I would just stick with attested cirban.