Earning, n.; pl. Earnings (. — Webster enters it under “earning”
That which is earned; wages gained by work or services; money earned; -- used commonly in the plural. As to the common people, their stock is in their persons and in their earnings. Burke.
Shades of meaning
Fernald has no entry of its own for earnings; he lists it under pay.
Where he writes about it:
Recompense is a still wider and loftier word, with less suggestion of calculation and market value; there are services for which affection and gratitude are the sole and sufficient recompense; earnings, fees, hire, pay, salary, and wages are forms of compensation and may be included in compensation, remuneration, or recompense. — from pay
Earnings is often used as exactly equivalent to wages, but may be used with reference to the real value of work done or service rendered, and even applied to inanimate things; as, the earnings of capital. — from pay