Looking up...
the day immediately before the present day
She called me yesterday to discuss the project.
This means she called the day before today.
Yesterday was a rainy day.
This describes the weather conditions the day before today.
Yesterday is a temporal adverb that refers to the previous day.
Yesterday is often used in casual conversation to refer to recent events or actions that occurred the day before.
Yesterday always refers to the day immediately before the present day, not any other day in the past.
From Middle English 'yester-day', from Old English 'ġisterdæg' (literally 'evening of the day before'), from 'ġeostor' (yester) + 'dæg' (day).
Yesterday is always used to refer to the day before the current day. It is not used to refer to any other day in the past.