37 USC 401 - Definitions

(a) Dependent Defined.— 
In this chapter, the term dependent, with respect to a member of a uniformed service, means the following persons:
(1) The spouse of the member.
(2) An unmarried child of the member who
(A) is under 21 years of age;
(B) is incapable of self-support because of mental or physical incapacity and is in fact dependent on the member for more than one-half of the childs support; or
(C) is under 23 years of age, is enrolled in a full-time course of study in an institution of higher education approved by the Secretary concerned for purposes of this subparagraph, and is in fact dependent on the member for more than one-half of the childs support.
(3) A parent of the member if
(A) the parent is in fact dependent on the member for more than one-half of the parents support;
(B) the parent has been so dependent for a period prescribed by the Secretary concerned or became so dependent due to a change of circumstances arising after the member entered on active duty; and
(C) the dependency of the parent on the member is determined on the basis of an affidavit submitted by the parent and any other evidence required under regulations prescribed by the Secretary concerned.
(4) An unmarried person who
(A) is placed in the legal custody of the member as a result of an order of a court of competent jurisdiction in the United States (or Puerto Rico or a possession of the United States) for a period of at least 12 consecutive months;
(B) either
(i) has not attained the age of 21;
(ii) has not attained the age of 23 years and is enrolled in a full time course of study at an institution of higher learning approved by the Secretary concerned; or
(iii) is incapable of self support because of a mental or physical incapacity that occurred while the person was considered a dependent of the member or former member under this paragraph pursuant to clause (i) or (ii);
(C) is dependent on the member for over one-half of the persons support;
(D) resides with the member unless separated by the necessity of military service or to receive institutional care as a result of disability or incapacitation or under such other circumstances as the Secretary concerned may by regulation prescribe; and
(E) is not a dependent of a member under any other paragraph.
(b) Other Definitions.— 
For purposes of subsection (a):
(1) The term child includes
(A) a stepchild of the member (except that such term does not include a stepchild after the divorce of the member from the stepchilds parent by blood);
(B) an adopted child of the member, including a child placed in the home of the member by a placement agency (recognized by the Secretary of Defense) in anticipation of the legal adoption of the child by the member; and
(C) an illegitimate child of the member if the members parentage of the child is established in accordance with criteria prescribed in regulations by the Secretary concerned.
(2) The term parent means
(A) a natural parent of the member;
(B) a stepparent of the member;
(C) a parent of the member by adoption;
(D) a parent, stepparent, or adopted parent of the spouse of the member; and
(E) any other person, including a former stepparent, who has stood in loco parentis to the member at any time for a continuous period of at least five years before the member became 21 years of age.