Ibis and emus and asps! Oh, my!

Crosswords are populated by unusual names and nouns such as these, as necessary to the grid as eggs to an omelet. These three- and four-letter staples hold together everything from five-star cruciverbalist concoctions to simple everyday fare. Without them, things fall apart. The center cannot hold.

To regular puzzlers, there is no need to explain that the answer to the clue “needle case” is “etui,” that the definition of “laic” is “non-clergy,” and that an “obi” is the sash of a kimono.

Greats on the grid are not Picasso or Renoir but Erte and Arp (father of Dada, another puzzle word).

And Olivier is no Esai (Morales), (Theda) Bara or Emil (Jannings — the first person presented with an Oscar) — nor is he an Uma (Thurman) or Uta (Hagen).

Sorry, Sarah Vaughan. The divas are Ella and Etta and Yma (Fitzgerald, James and Sumac). But Gaga is gaining.

Common flora include the lily and iris; common fauna, the ibis, emu and asp.

Aces in sports are Ott (baseball’s Mel) or Orr (hockey’s Bobby).

What world leaders do appear on the grid tend to be Asian; Mao and Deng, of course, but on occasion, U Nu. (Former prime minister of Burma. Who knew?)

And no roundup of words would be complete without mentioning that top dog, the mascot of all crosswords, the leader of the pack, Asta.

Oh — and Toto, too.

Donna Peremes proofs the daily crossword puzzle for The Washington Post.