re·sid·u·um
noun/rɪˈzɪdjuəm/
/rɪˈzɪdʒuəm/
(plural residua
(specialist)/rɪˈzɪdjuə/
/rɪˈzɪdjuə/
)- something that remains after a reaction or process has taken place
（化学反应的）残基，残渣，残留物；（某种进程的）残体 Word Originlate 17th cent.: from Latin, neuter of residuus ‘remaining’, from the verb residere.