La palabra del día: Cumplir

Verb. From the Latin complere, to fulfil, to complete, to finish. Verb formed by the prefix con- (joint action) and the verb plere (to fill).
In Legal Spanish means to do what one must or what one is obliged to do. It is used in expressions as cumplir un contrato o incumplir un contrato. Noun: el cumplimiento/incumplimiento de un contrato: fulfilment/breach of contract.
The verb cumplir is used also to say cumplir años and it is the root of the noun cumpleaños: birthday. Hoy cumplo años, hoy es mi cumpleaños. A curiosity, we cannot say el cumplimento de años. dc.