Is it farther or further?
"nothing," 1966, from earlier sense of "meaningless speech" (1960), originally Mr. Zilch (1931), comic character in the magazine "Ballyhoo." Perhaps from U.S. college slang (early 1900s) Joe Zilsch "an insignificant person." Probably a nonsense syllable, but Zilch is an actual German surname of Slavic origin.
Some sleep; a nap: If he wants a few zees we can go on automaticverb
To sleep; snooze; cop zs: Gotta Z a little while
[1960s+; fr the conventional sibilant or buzzing sound attributed to a sleeping or snoring person]