物理學上指作用於物體嘅力大小相等，而喺作用嘅同一時間內，產生相等而相反嘅動量 ((physically) to rebound; to react)
動詞Examples
佢掟個波埋牆，結果個波反彈打中自己。
keoi5 deng3 go3 bo1 maai4 coeng4, git3 gwo2 go3 bo1 faan2 daan6 daa2 zung3 zi6 gei2.
He throws the ball to a wall where it rebounds and hits himself.
因為環境對心理構成嘅壓力而反感、不忿 (to rebound to mental pressure)
Examples
公司唔合理噉加班，引起咗部分員工情緒上嘅反彈。
gung1 si1 m4 hap6 lei5 gam2 gaa1 baan1, jan5 hei2 zo2 bou6 fan6 jyun4 gung1 cing4 seoi5 soeng6 ge3 faan2 daan6.
The unreasonable arrangement of overtime work by the company irritated a number of its staff.
金融術語。喺空頭市場裏，由於股價、匯價大幅下跌已有一段時間，由低檔暫時回升 ((of financial terms) to rebound)
Examples
股市經過多日跌勢，今日反彈回升至日前高位。
gu2 si5 ging1 gwo3 do1 jat6 dit3 sai3, gam1 jat6 faan2 daan6 wui4 sing1 zi3 jat6 cin4 gou1 wai2.
The stock market saw a downward trend for the last few days, but today it rebounded to reach a previous day's high.