Construct:	Noun
Definition:	A small quantity (of liquid) provided by the supplier in addition to the standard measure (term usually employed with reference to milk supply in the days when milk was distributed out of churns).
Use:
Derivation:	Probably Irish 'Tuilleadh' - act of addition to or increasing. (Dinneen). 'Tilly' - something additional and of small value given into the bargain as a gift or bonus. A small ewer of milk given to a servant by a milkman over and above that for use by the family. (Wright).