| Ökostrom | clean power eco-power |
| Ökoton | ecotone |
| Ökonom | economist |
| Kostüm | suit costume fancy dress |
| Kolostrum | colostrum beestings foremilk |
| rostrot | auburn |
| Angström | angstrom |
| Atomstrom | electricity generated by nuclear power |
| Golfstrom | Gulf Stream |
| Strom | current torrent stream |
| Ångström | angstrom ångström |
| Ökotyp | ecotype |
| Kokosöl | coconut oil |
| Zökostomie | caecostomy cecostomy |
| Ökonym | econym |
| Ökosystem | ecosystem |
| Kosmodrom | cosmodrome |
| Koseform | affectionate form familiar form |
| Kosmos | cosmos |
| Kosovo | Kosovo |