The word interjection is a noun. The plural form is interjections.
interjection
It is an Interjection.
interjection
Interjection
adverb/interjection
Ugh is an interjection.
Eureka is an interjection.
It's an interjection.
"Ha" is an interjection.
- interjection / verb / noun goodbye - interjection / noun
The part of speech for "yo" is interjection. EXAMPLE: Yo! What's up?
Maybe an interjection?