From Battlestar Wiki, the free, open content Battlestar Galactica encyclopedia and episode guide
Chrome dome is a nickname for a Cylon that has been used in both Galactica 1980 and the Re-imagined Series.
In Galactica 1980, this nickname for Centuri (a Centurion) is given by a thug whose "territory" is in Central Park. The thug uses the term when being questioned by the NYPD chief, piquing the attention of USAF Colonel Briggs, who is within earshot (1980: "The Night the Cylons Landed, Part II").
In the Re-imagined Series, the name is thrown out by the tattooed pilot in the rec room on Galactica when attempting to find a callsign for Sharon Agathon (TRS: "Torn").