Ignorar vs. hacer caso omiso vs. no hacer caso

In Spanish, 'ignorar', 'hacer caso omiso' and 'no hacer caso' all mean to ignore or disregard something or someone in some way. While their meanings are similar, they are used in slightly different contexts and can convey different nuances of meaning.

Ignorar

'Ignorar' typically refers to lacking knowledge about something or deliberately not paying attention or ignoring something or someone.
Ella decidió ignorar las críticas destructivas.
(She decided to ignore the destructive criticisms.)
Ignoro la causa de su enojo.
(I ignore the cause of his anger.)

Hacer caso omiso

'Hacer caso omiso' means intentionally disregarding something, such as an advice, rule, or particular situation. This expression conveys the idea of deliberately ignoring with intent.
Decidió hacer caso omiso de las advertencias de seguridad.
(He decided to disregard the safety warnings.)
Se hacen caso omiso a las normas de la comunidad.
(The community rules are being disregarded.)

No hacer caso

'No hacer caso' is used in everyday spoken language and has a softer tone. This term is usually used in less formal situations and often refers to not paying attention to someone or something.
Ella no hace caso a los rumores.
(She pays no attention to the rumors.)
Mi hermano no me hace caso cuando estoy hablando.
(My brother doesn’t listen to me when I'm talking.)

Summary

'Ignorar', 'hacer caso omiso' and 'no hacer caso' all have translations relating to ignoring or disregarding in English language. However, 'ignorar' often implies lack of knowledge or intentional neglecting; 'hacer caso omiso' emphasizes on purposeful disregard; and 'no hacer caso' often conveys lack of attention, commonly in informal situations.