/əˈklɒk ||; əˈklɑk/adv used after the numbers one to twelve for saying what the time is （用于一至十二的数字后，表示某一点钟）: Lunch is at twelve o'clock. 午饭在十二点正。 Be careful. o'clock can only be used with full hours We arranged to meet at 5 o'clock. It's 5.30 already and he's still not here. 注意：o'clock只用于指整点：We arranged to meet at 5 o'clock. It's 5.30 already and he's still not here.我们安排在5点钟见面，现在已是5点30分，可是他还没来。