Tedious; boring; dull—lacking interest or excitement.
この授業は退屈で眠くなる。
This class is boring and makes me sleepy.
退屈な映画だった。
It was a boring movie.
週末が何もなくて退屈だ。
The weekend is boring because there's nothing to do.
To feel bored; to become bored (to be uninterested or weary of something).
長い会議で誰もが退屈していた。
Everyone was bored during the long meeting.
子どもが退屈しないように遊びを用意した。
I prepared games so the children wouldn't get bored.
毎日同じ繰り返しで退屈する。
I get bored with the same routine every day.