gender based on the sex or, for neuter, the lack of sex of the referent of a noun, as English girl (feminine) is referred to by the feminine pronoun she, boy (masculine) by the masculine pronoun he, and table (neuter) by the neuter pronoun it.
Compare grammatical gender.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for natural gender
grammatical gender that reflects, as in English, the sex or animacy of the referent of a noun rather than the form or any other feature of the word
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012