Stretching the back or standing on tiptoe to make oneself taller; the physical act of stretching one's body.
朝、目が覚めたらまずベッドの上で背伸びをする。
When I wake up in the morning, I first stretch on the bed.
彼女は棚の上の箱を取ろうと背伸びしたが、届かなかった。
She stood on tiptoe and stretched to reach the box on the top shelf, but couldn't reach it.
長時間座った後に背伸びをすると気分がすっきりする。
Stretching after sitting for a long time refreshes you.
Overreaching oneself; trying to do something beyond one's ability or pretending to be bigger or more capable than one is.
給料がそんなにないのに高級マンションに引っ越すなんて、ちょっと背伸びだよ。
Moving into an expensive apartment when your salary doesn't allow it is a bit of overreaching.
彼は社交の場で背伸びをして知らない話題にも首を突っ込んだが、すぐに困った。
He tried to show off at the social gathering and got involved in topics he didn't know, but soon ran into trouble.
親が子どもに高価な習い事をたくさんさせるのは、時に親の背伸びになることがある。
Parents making their children do many expensive lessons can sometimes be the parents overreaching.