a structure, consisting of an overhead cable, that is used to deliver electric current to an electric railway locomotive or tram, any flexible wire or cable freely suspended at two points and supporting its own weight alone, will assume a definite curve, known as the catenary, liin, mille juhid kulgevad maapinna kohal ja on mingi kindla vahemaa järel kinnitatud mastide vm tarindite külge. Õhuliine kasutatakse peamiselt elektrienergia edastamiseks (elektri-õhuliin), kuid ka