Calendar quarter.

Calendar quarter. A 3-month period during the year as follows: January 1 through March 31; April 1 through June 30; July 1 through September 30; and October 1 through December 31.

Source

27 CFR § 25.11

Scoping language

When used in this part, where not otherwise distinctly expressed or manifestly incompatible with the intent thereof, terms have the meanings given in this section.