The Collaborative International Dictionary of English v.0.48:
Secundo-geniture \Se*cun`do-gen"i*ture\, n. [L. secundus second + genitura a begetting, generation.] A right of inheritance belonging to a second son; a property or possession so inherited. [1913 Webster] The kingdom of Naples . . . was constituted a secundo-geniture of Spain. --Bancroft. [1913 Webster]