WordNet sense 1 (a line or route along which something travels or moves):

path, track

WordNet sense 2 (general line of orientation):

trend

WordNet sense 3 (a connected series of events or actions or developments):

line

WordNet sense 4 ((construction) a layer of masonry):

row, row

WordNet sense 5 (move along, of liquids):

feed, flow, run

WordNet sense 6 (education imparted in a series of lessons or meetings):

class, course of study, course of instruction

WordNet sense 7 (as might be expected):

naturally, of course

WordNet sense 8 (a mode of action):

course of action