Alternative term: Base (U.S.A.)
That part of a lamp which holds it in a lampholder and usually provides connection to the electric supply.
Note: The cap (base) of a lamp and its corresponding holder (socket) are generally identified by one or more letters followed by a number which indicates approximately the principal dimension (generally the diameter) of the cap in millimetres.
For more information, see I.E.C. Recommendations Publication No.61 "Lamp caps and holders together with gauges for the control of interchangeability and safety".
Reference: C.I.E. (modified)
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
Celsius (previously Centigrade)
Number of cells
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM