WordNet sense 1 (a sequentially ordered set of things or events or ideas in which each successive member is related to the preceding):

string

WordNet sense 2 (a procession (of wagons or mules or camels) traveling together in single file):

caravan, wagon train

WordNet sense 3 (public transport provided by a line of railway cars coupled together and drawn by a locomotive):

railroad train

WordNet sense 4 (wheelwork consisting of a connected set of rotating gears by which force is transmitted or motion or torque is changed):

gear, gearing, geartrain, power train

WordNet sense 5 (train by instruction and practice; especially to teach self-control):

check, condition, discipline

WordNet sense 6 (train to be discriminative in taste or judgment):

civilize, cultivate, educate, school, civilise

WordNet sense 7 (prepare (someone) for a future role or function):

groom, prepare

WordNet sense 8 (travel by rail or train):

rail

WordNet sense 9 (drag loosely along a surface; allow to sweep the ground):

trail

WordNet sense 10 (aim or direct at; as of blows, weapons, or objects such as photographic equipment):

aim, direct, take, take aim

WordNet sense 11 (teach and supervise (someone); act as a trainer or coach (to), as in sports):

coach

WordNet sense 12 (create by training and teaching):

develop