1 [C] a large, important organization that has a particular purpose, such as a bank, a university, etc （有特定目的的）大机构（如银行、大学等）: the financial institutions in the City of London 伦敦商业区的金融机构

2 [C] a building where certain people with special needs live and are looked after 为有特殊需要者设立的建筑物: a mental institution (= a hospital for the mentally ill) 精神病院She's been in institutions all her life. 她在不同的特殊服务机构里度过了一辈子。

3 [C] a social custom or habit that has existed for a long time 习俗；惯例: the institution of marriage 婚姻制度

4 [U] the act of introducing a system, policy, etc, or of starting a process 建立；设立；制定: the institution of new safety procedures 制定新的安全程度