Consequently, -ek and the intermorph -o- in bawidamek 'ladies' man' are treated as co-formatives by Szymanek (2010, 223). In (3) examples are provided of Polish compounds proper which consist of two nominal stems linked by the intermorph -o-. They can be treated as coordinate structures […] a. barman-o-kelner / bartender-INTERFIX-waiter / 'a bartender and waiter' / b. chlop-o-robotnik / peasant-INTERFIX-worker / 'a peasant farmer who works in a factory' / c. klub-o-kawiarnia / club-INTERFIX-cafè / 'a cafè that hosts cultural events' / d. kurs-o-konferencja / training-INTERFIX-conference / 'a training conference' / e. spódnic-o-spodnie / skirt-INTERFIX-trousers / 'skort, culottes' / f. gad-o-ptak / reptile-INTERFIX-bird / 'archaeopteryx'
Source: wiktionary