Answer:
The tip-of-the-tongue phenomenon
Step-by-step explanation:
The Tip-of-the-tongue phenomenon, also referred to as TOT, is a situation in which a person struggles to remember the name of a word. However, usually the person is able to partially remember the initial sound of the word, its meaning, or the first letter of the term.
According to research, elderly people are more often associated with this phenomenon as it becomes more common.
Therefore, Karen's grandmother, struggling to remember the term 'coffee mug' may be experiencing the tip-of-the-tongue phenomenon.