西漸せいぜん Noun Irregular Intransitive English jmdict 1 noun (common) (futsuumeishi) noun or participle which takes the aux. verb suru intransitive verb westward advance
西漸運動せいぜんうんどう Noun English jmdict 1 noun (common) (futsuumeishi) historical term Westward movement (westward expansion of United States territory)