Gendered Nouns

Many nouns that denote people specify the gender of the person with noun endings. If the partner is female, the noun ends in "-in." In English, the gender of the person is not expressed linguistically. Even in cases where English speakers can make such a distinction (e.g. actor/actress), users of the language are shifting away from doing so.
Male FemaleEnglish

der Freund

die Freundinfriend
der Partnerdie Partnerinpartner
der Lebensgefährtedie Lebensgefährtinsignificant other
der Kundedie Kundincustomer
der Verkäuferdie Verkäuferinsalesperson
der Studentdie Studentincollege student
der Professordie Professorinprofessor
der Schauspielerdie Schauspielerinactor