1Describes what is true in most cases; means 'usually' or 'normally.'
たいていの学生は朝の授業に出席する。
Most students attend the morning classes.
たいていは予約が必要だが、今日は空いているかもしれない。
Usually you need a reservation, but today it might be open.
彼の話はたいてい面白い。
His stories are usually interesting.
2Similar to 'probably,' expressing the speaker's conjecture about something.
彼はたいてい遅刻するから、今日も遅れるだろう。
He usually arrives late, so he'll probably be late today too.
たいていの人はその説明で納得するだろう。
Most people will probably be satisfied with that explanation.
3Used in the form 「たいていの〜」 to mean 'most' or 'almost all' of something.
たいていの人は朝食を食べる。
Most people eat breakfast.
その本はたいていの書店で手に入る。
That book is available at most bookstores.
4Used together with a negative form to mean 'usually not,' indicating that exceptions are rare.
たいていはそんなに困らないが、今回は違う。
Usually it's not that troublesome, but this time it's different.
彼はたいてい怒らないが、今日は珍しく怒った。
He usually doesn't get angry, but he was unusually angry today.
5Refers to a proper or moderate degree; often used in the pattern 「〜にする」 to mean 'to keep something in moderation' or 'to stop overdoing something.'
飲み会はたいていにしておきなさい。
Keep the drinking party moderate — don't overdo it.
その冗談はたいていにしなさい。みんな不快に思っているよ。
That's enough with the joke. Everyone is uncomfortable.