noun / adjective
myriad
MEER-ee-ud/mˈɪriʌd/
A very large or countless number.
A myriad of small fish fills the densely packed shoal.

Etymology
Greek myrias could mean either a group of ten thousand or countless numbers. The English sense preserves that expansive use, expressing a vast quantity rather than an exact count.
In context
There are billions of them in one compost heap, more than there are people on Earth. A myriad of fruit flies is also drawn to the fermenting mass.
More examples
- The project faces myriad challenges.
- Myriads of stars fill the clear night sky.
- She finds a myriad of ways to save money.
Forms
myriad · myriads
Similar words
- multitude
- A large number, without implying that counting is impossible.
- countless
- Describes things too numerous to count; used only adjectivally.