Sometimes, we use the connector -er for words that get -eren the plural for (see [plural nouns](#/lesson/NounsAndArticles.13)).
het kind + de wagen | de kinderwagen | the buggy
het ei + de dooier | de eierdooier | the egg-yolk
het kalf + de liefde | de kalverliefde | the ('calf') love between teenagers
het rund + het gehakt | het rundergehakt | the minced beef
The connector -er is very uncommon. Even words that take -eren as a plural ending, usually get -e, -en, -s.
Next to kalverliefde, we also have kalfskarbonade (veal-cutlet), next eierdooier also eiwit (protein) and eicel (egg-cell), and next to rundergehakt also rundvlees (beef).