sue (v.)

c. 1400, "seek after, pursue; follow (a path)," from Old French ensu-, past participle stem of ensivre "follow close upon, come afterward," from Late Latin insequere, from Latin insequi "to pursue, follow, follow after; come next," from in- "upon" (from PIE root *en "in") + sequi "follow" (from PIE root *sekw- (1) "to follow"). Early 15c. as "follow (as a consequence), to result;" mid-15c. as "to follow" in time or space, "to come or appear next, be subsequent to, happen subsequently." Related: Ensued; ensues; ensuing.

late 13c., "follow with hostile intent, follow with a view of overtaking," from Anglo-French pursuer and directly from Old French poursuir (Modern French poursuivre), variant of porsivre "to chase, pursue, follow; continue, carry on," from Vulgar Latin *prosequare, from Latin prosequi "follow, accompany, attend; follow after, escort; follow up, pursue," from pro- "forward" (see pro-) + sequi "follow" (from PIE root *sekw- (1) "to follow").

The meaning "to proceed, to follow" (a path, etc.), usually figurative (in reference to a course of action, etc.), is from late 14c. This sense also was in Latin. The meaning "seek, seek to obtain" also is late 14c. Related: Pursued; pursuing. For sense, compare prosecute.