The Elvish word rath originally meant 'climb', used especially for a stretch of path or roadway climbing up into hills (for example, Cirith Forn en Andrath, 'northern pass of the long climb', was the Elvish name for the High Pass through the Misty Mountains). For historical reasons, the word came to be used by the Dúnedain for 'street' or 'roadway', so for example Rath Celerdain in Minas Tirith was the 'Lampwrights' Street', not the 'Lampwrights' Climb'). Either meaning might in principle apply to Andrath, but in practice 'long climb' seems to be the intended meaning, especially since the North-South Road ran through hilly country along this stretch of its length.