the 1st month of the year, between December and February 一月 She was born in January. 她出生于一月。 - (British English)
The meeting is on the fifth of January/January the fifth. 会议在1月5日/1月5日举行。 - (North American English)
The meeting is on January fifth. 会议在1月5日。 We went to Japan last January. 我们去年一月去了日本。 I arrived at the end of January. 我是一月底到的。 last January's election 去年一月的选举 the January sales (= when a shop sells its goods at a lower price than usual) 元月大减价 It was a cold January morning. 那是一个寒冷的一月早晨。
Word OriginOld English, from Latin Januarius (mensis) ‘(month) of Janus’, the Roman god who presided over doors and beginnings.