Tare and Tret, in commerce, allowances or deductions.
Tare is an allowance made from the gross weight of goods for the box, bag or other wrapping in which the goods are packed. It may be real, i.e. representing the actual weight of the wrapping; customary, when a uniform or established rate is allowed; average, when one or two packages among several are weighed, and the mean or average of the whole taken; or super-tare, an additional allowance when the package exceeds a certain weight. Tret is an allowance of 4 lb. in every 104 lb. of weight, made as compensation for loss by waste.
'Tare' comes through the French tare, cf. Spanish tara, from Arabian tarha, tarh, throwing, casting - the word meant originally loss, that which is thrown away; 'tret' is an adaptation of French traite, Latin trahere, to draw, and meant a draught, transportation, also a payment on exports, an allowance on exportation.
Being the entry for TARE AND TRET in the 1911 Encyclopedia Britannica, the text of which lies within the public domain.