Diario vs. cotidiano
The Spanish words diario and cotidiano both translate to daily, meaning something that occurs every day. However, there are subtle differences in their usage and connotations.
Diario
A2Diario literally translates to daily in English and is usually used to suggest routines or activities that occur every single day. It can refer to both human actions (like eating) and natural phenomena (like sunrise).
Hago ejercicio diario para mantenerme en forma.
(I exercise daily to stay fit.)
El periódico diario trae las noticias más recientes.
(The daily newspaper brings the latest news.)
Cotidiano
B1Cotidiano also means daily, but it generally refers more to everyday life, suggesting something ordinary or routine. It can sometimes carry a connotation of mundanity.
Las tareas cotidianas pueden ser aburridas.
(Everyday tasks can be boring.)
El ruido del tráfico es una parte cotidiana de la vida en la ciudad.
(Traffic noise is an everyday part of life in the city.)
Summary
Diario and cotidiano both translate to daily in English but their usage varies slightly depending on context. Diario is often used for activities or items that occur or are used every day, such as exercise or a newspaper. On the other hand, cotidiano leans more towards everyday life experiences or things that are ordinary and commonplace.