Opposite words for myriad:
unmixed, only, homogeneous, limited, distinct, distinctive, identical, singular, numberable, unvaried, alike, separate, monolithic, solitary, calculable, alone, same, finite, individual, unique, homogenous, sole, enumerable, lone, countable.
Usage samples:
  1. And clinging to my little windows were myriad tiny bubbles that rose slowly.
    "Careers of Danger and Daring", Cleveland Moffett.
  2. The thought of being lost in Thorn's Gulch, or in some one of the myriad branches of the majestic chasm that extended for hundreds of miles in the course of the mighty Colorado, was alarming.
    "The Go Ahead Boys and Simon's Mine", Ross Kay.
  3. It is simply another example of that complicated struggle for existence, by means of which nature keeps ever a fairly even balance of her myriad forces.
    "Butterflies Worth Knowing", Clarence M. Weed.
  4. But with the mention of Mr. Laurie myriad dreams had flashed into his mind.
    "Ted and the Telephone", Sara Ware Bassett.