Collateral Descendant Definition: A descendant that is not direct, such as a niece or a cousin. Related Terms: Lineal Descendant, Next of Kin "A collateral descendant is a niece or nephew of his or her uncle or aunt."These words were used by Madam Justice Russell of the Supreme Court of British Columbia in Burnaby Greenhouse, at ¶13.A descendant that is not direct (i.e. collateral), such as a niece or a cousin.University of Detroit law professor Merle Brake wrote, in 1953:"Descendants are either lineal or collateral.A lineal descendant is one in the direct line of descent.A collateral descendant is one descended from the same ancestor but not in the same line, e.g. brothers and sisters."REFERENCES:Brake, Merle E., The Beginnings of Property Law--Part III: The Evolution of Conveyancing, 16 U. Det. L.J. 61 (1952-1953), at page 71 (footnote)Burnaby Lake Greenhouses v. Her Majesty The Queen In Right Of The Province Of British Columbia, 2005 BCSC 1682 Categories & Topics: Trusts, Wills, Estates and Probate Law Dictionary Find you are constantly looking up definitions? Try our search provider (works in most modern browsers) If you find an error or omission in Duhaime's Legal Dictionary, or if you have legal term suggestion, we'd love to hear from you!