The pharmacy department is absent today, eh?
I fired him because he no call no show'd three times in row.
I’m terribly sorry, but an urgent business trip has come up, so I’ll be absent from the reunion party tonight.
When a seat is lacking the person it's supposed to have in it, there is an absence. Where is Johnny? Another absence? Ugh. Johnny. C'mon.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well. Note that the けつ is shortened to けっ as つs often are when in a situation like this.