熟達じゅくたつ Noun Irregular Intransitive English jmdict 1 noun (common) (futsuumeishi) noun or participle which takes the aux. verb suru intransitive verb mastery ２、３年でフランス語に熟達するのはきわめて難しい。 It's quite difficult to master French in 2 or 3 years.
Shirabe