(1) Except as provided in paragraph (bbb)(2) of this section, transaction means a purchase, sale, loan, pledge, gift, transfer, delivery, or other disposition, and with respect to a financial institution includes a deposit, withdrawal, transfer between accounts, exchange of currency, loan, extension of credit, purchase or sale of any stock, bond, certificate of deposit, or other monetary instrument, security, contract of sale of a commodity for future delivery, option on any contract of sale of a commodity for future delivery, option on a commodity, purchase or redemption of any money order, payment or order for any money remittance or transfer, purchase or redemption of casino chips or tokens, or other gaming instruments or any other payment, transfer, or delivery by, through, or to a financial institution, by whatever means effected.
(2) For purposes of §§ 1010.311, 1010.313, 1020.315, 1021.311, 1021.313, and other provisions of this chapter relating solely to the report required by those sections, the term “transaction in currency” shall mean a transaction involving the physical transfer of currency from one person to another. A transaction which is a transfer of funds by means of bank check, bank draft, wire transfer, or other written order, and which does not include the physical transfer of currency, is not a transaction in currency for this purpose.
31 CFR § 1010.100
When used in this chapter and in forms prescribed under this chapter, where not otherwise distinctly expressed or manifestly incompatible with the intent thereof, terms shall have the meanings ascribed in this subpart. Terms applicable to a particular type of financial institution or specific part or subpart of this chapter are located in that part or subpart. Terms may have different meanings in different parts or subparts.