◎ 三通 sāntōng
(1) [tee]∶有橫向出口的短管,用于連接與該管成直角的管道
(2) [three-way pipe]∶以45°從主直管分出的支管,即Y形接管頭

1.{機} triplet; tee; tee joint; {工} wye; Y; yoke
2.（指通郵、通商、通航） “three exchanges”: exchanges of mails, trade, air and shipping services; the opening of postal, aviation and navigational services and commercial interflow
名詞1.（政）Three Direct Links (direct links in post, transportation and trade between the Chinese mainland and Taiwan)

唐 杜佑 《通典》、 宋 鄭樵 《通志》、 元 馬端臨 《文獻通考》的合稱。 清 鈕琇 《觚賸續(xù)編·三通》：“人而不讀三通，安得謂之通？三通者， 杜佑 《通典》， 鄭樵 《通志》 馬端臨 《文獻通考》也?！?/p>