level: [14] The Latin word for a ‘balance’ or ‘scales’ was libra (it has given English Libra the zodiacal sign [14] and also lies behind many terms for units of measurement, including litre and the abbreviation lb for ‘pound’). Its diminutive form was lībella, which denoted an ‘instrument for checking horizontality’, and hence a ‘horizontal line’. It passed into Old French as livel (which in modern French has become niveau ‘level’), and English took it over as level. => litre[level etymology, level origin, 英语词源]