a.m.

英 [ˌeɪ ˈem]

美 [ˌeɪ ˈem]

abbr. 午夜至正午，上午，午前(源自拉丁语ante meridiem)

Collins.2

牛津词典

abbr.

午夜至正午，上午，午前（源自拉丁语ante meridiem）
between midnight and midday (from Latin ante meridiem )
1. It starts at 10 a.m.
  上午10点开始。

上午；午前
a.m. is used after a number to show that you are referring to a particular time between midnight and noon.
1. The program starts at 9 a.m.
  节目上午9点开始。

adj

A.m. I woke up at four in the morning.
6点。我早上4点就醒了。
I pored over the books with great enthusiasm, often crunching the numbers until 1:00 a.m.
我兴致勃勃地研究这些账簿，经常计算到凌晨1点。
His workday starts at 3.30 a.m. and lasts 12 hours.
他凌晨3点半开始工作，一直持续12小时。
Sometimes I'd even call up at 4 a.m.
有时我甚至早上四点都打电话。
Two people in the flat recalled hearing a loud crash about 1.30 a.m.
公寓楼里有两个人回想起凌晨1点半听见了一声巨响。
The interview was9 a.m., I arrived a quarter earlier.
面试时间定在今天早上九点。我提前一刻钟到了。
The Visitor Centre is open daily 8.30 a.m. – 4.30 p.m.
游客中心每日上午8:30至下午4:30开放。
I spotted a clock: 3:00 a.m.
我看了一眼钟：凌晨2点。
He once sleepwalked to the middle of the road outside his home at 1 a.m.
有一次，他在凌晨1点钟梦游走到了家门外的马路中央。
Can I get a seat for today's 7:00 a.m. train?
我可以买到今天上午7点的火车座位吗？