In English, name Lionel means – Young lion. Diminutive of Leon. One of the knights of King Arthurs Round Table. Famous Bearers: American actor Lionel Barrymore (1878-1954) and British actor Lionel Jeffries (born 1926).. Other origins for name Lionel include – English, French, French. Name Lionel is most often used as a boy name or male name.