(1) the term employee means an employee as defined by section 6301 (2), excluding an individual employed by the government of the District of Columbia;

(2) the term leave recipient means an employee whose application to receive donations of leave under this subchapter is approved;

(3) the term leave donor means an employee whose application to make 1 or more donations of leave under this subchapter is approved; and

(4) the term medical emergency means a medical condition of an employee or a family member of such employee that is likely to require the prolonged absence of such employee from duty and to result in a substantial loss of income to such employee because of the unavailability of paid leave (disregarding any advanced leave).