Fetching details from the dictionary...

tedious; boring; dull; uninteresting; tiresome; monotonous
to feel bored; to get bored (with); to get tired (of)
彼の話は退屈で全く面白くなかったです。
His story was boring and not interesting at all.
長い会議で退屈して眠くなってしまった。
I got bored and sleepy during the long meeting.
退屈な授業で眠くなる。
I get sleepy in boring classes.