Business day. This term means any day other than a Sunday or holiday. In all notices required by the Act or by the rules and regulations in this chapter to be given in terms of business days the rule for computing time shall be to exclude the day on which notice is given and include the day on which shall take place the act of which notice is given.
17 CFR § 1.3
Words used in the singular form in the rules and regulations in this chapter shall be deemed to import the plural and vice versa, as the context may require. The following terms, as used in the Commodity Exchange Act, or in the rules and regulations in this chapter, shall have the meanings hereby assigned to them, unless the context otherwise requires: