Words or sayings that are in common use; names that are familiar to everyone.
Who coined the term ‘household words’? The most common answer to any question beginning ‘Who coined the phrase …’ is William Shakespeare and, as so often, the bard doesn’t disappoint. This one comes from the celebrated Saint Crispin’s Day speech in Henry V, 1598:

He that shall live this day, and see old age,
Will yearly on the vigil feast his neighbours,
And say ‘To-morrow is Saint Crispian:’
Then will he strip his sleeve and show his scars.
And say ‘These wounds I had on Crispin’s day.’
Old men forget: yet all shall be forgot,
But he’ll remember with advantages
What feats he did that day: then shall our names.
Familiar in his mouth as household words