Nkran is an Akan word meaning 'ants', from which the name Accra is derived, referring to soldier ants and the anthills around the area. Wikipedia reports that the historian C. C. Reindorf supported this etymology and proposed a link between the martial and migratory qualities of the ants and those of the Ga; in Ga itself the city is called Gã (Gãgã).
The name Accra is often traced to the Akan word nkran.