Definition of seminal. 1 : of, relating to, or consisting of seed or semen. 2 : containing or contributing the seeds of later development : creative, original a seminal book. It might be said that the preamble from the Universal Declaration of Human Rights might be considered a seminal document because it is the introduction to the Declaration of Human Rights, as well as , it sets out the ideas and values for the rest of the document. relating to the commissioning or preparing of material for publication.