legal ouster le·ga·lous·ter uncommon noun 1. the expulsion of someone (such as a tenant) from the possession of land by process of law Synonymsevictiondispossessionlegal ouster Related words Word family dispossessevict Broader terms due process Narrower terms ousteractual evictionretaliatory eviction WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.