20 C.F.R. § 222.2
As used in this part-
Annuity means a payment under the Railroad Retirement Act due to an entitlement claimant for a calendar month and made to him or her on the first day of the following month.
Apply means to sign a form or statement that the Railroad Retirement Board accepts as an application for an annuity or lump-sum payment under the rules set out in part 217 of this chapter.
Child has differing definitions for annuity and lump-sum payment purposes. See § 222.31 .
Claimant means a person who files an application for an annuity or lump-sum payment or for whom an application is filed.
Eligible means that a person would meet all the requirements for payment of an annuity or lump-sum payment as of a given date but has not yet applied therefor.
Employee means an employee as defined in part 203 of this chapter.
Final divorce means a divorce that completely dissolves a marriage and restores the parties to the status of single persons; it is also referred to as an absolute divorce.
Finally divorced person means a person whose marriage has been terminated or dissolved by a final divorce.
Legal impediment means that there was a defect in the procedures followed in a marriage ceremony or that a previous marriage of the employee or spouse had not ended at the time of the ceremony.
Lump-sum payment means any of the following payments under the Railroad Retirement Act: lump-sum death payment, residual lump-sum, annuities due but unpaid at death, or lump-sum refund payment (see part 234 of this chapter).
Marriage means the social and legal relationship of husband and wife for family relationship purposes, as well as the act by which the married state is effected.
Permanent home means the employee's true and fixed home (legal domicile); it is the place to which the employee intends to return whenever he or she is absent therefrom.
Relationship means a family connection by blood, marriage, or adoption between the employee and another person who is a claimant.
Spouse means the husband or wife of the employee.
State law means the law of the State in which the employee has his or her permanent home or, in the case of a deceased employee, the law of the State in which the employee had his or her permanent home at the time of his or her death. If the employee's permanent home is not in one of the 50 States, the Commonwealth of Puerto Rico, the Virgin Islands, Guam, or American Samoa, the laws of the District of Columbia are applied.
20 C.F.R. §222.2