. . . payments made for occasional periods when no work is performed due to vacation, holiday, . . . or other similar cause.
As explained in 29 CFR 778.218(d) , the term "other similar cause" refers to payments made for periods of absence due to factors like holidays, vacations, illness, and so forth. Payments made to an employee for periods of absence due to the use of accrued compensatory time are considered to be the type of payments in this "other similar cause" category.
29 C.F.R. §553.26