What is Aliment?

Legal Definition
Aliment, in Scots law and in other civil systems, is the sum paid or allowance given in respect of the reciprocal obligation of parents and children, husband and wife, grandparents and grandchildren, to contribute to each other's maintenance. The term is also used in regard to a similar obligation of other parties, as of creditors to imprisoned debtors, the payments by parishes to paupers, etc.

Alimentary funds, whether of the kind above mentioned, or set apart as such by the deed of a testator, are intended for the mere support of the recipient, and are not attachable by creditors.
-- Wikipedia
Legal Definition
In the Roman and French law this word signifies the food and other things necessary to the support of life, as clothing and the like. The same name is given to the money allowed for aliments. Dig. 50, 16, 43.

2. By the common law, parents and children reciprocally owe each other aliments or maintenance. (q. v.) Vide 1 Bl. Com. 447; Merl. Rep. h. t.; Dig. 25, 3, 5. In the common law, the word alimony (q.v.) is used. Vide Allowance to a Prisoner.
-- Bouviers Law Dictionary
Legal Definition
In Scotch law. To maintain. support, provide for; to provide with necessaries. As a noun, maintenance, support ; an allowance from the husband's estate for the support of the wife. Paters. Comp. ยงยง 845, 850, 893.
-- Black's Law Dictionary