Annunaki

Do you have such cases when a word appears in your head and is in no hurry to leave it, the meaning of which you do not know?
For example, a month ago, I was walking along the embankment and the word "Annunaki" appeared in my head, just like that, with a double "n" after the first letter. "I'll come home, I'll take a look in Google" - I thought, but when I came I forgot it. Attempts to remember did not lead to anything, I remembered only that the word begins with "a". But now I remembered, checked, such a word exists.