Select the most appropriate meaning of the given idiom.

On the tip of my tongue

Readily available in my memory

The most appropriate meaning of the idiom "on the tip of my tongue" is readily available in my memory.

It is used to describe a word or phrase that is on the verge of being remembered. The idiom is thought to have originated from the idea that the tip of the tongue is the part of the tongue that is most sensitive to touch, and so it is the part of the tongue that is most likely to be used to recall a word or phrase.

For example, you might say "The name is on the tip of my tongue, but I just can't remember it." This means that you know the name, but you cannot quite remember it at the moment.

The other options are not accurate descriptions of the meaning of the idiom.

• Feeling extremely joyful: This idiom is more accurately described as "being on cloud nine."
• Excessively costly: This idiom is more accurately described as "being out of reach."
• At full speed: This idiom is more accurately described as "going full throttle."