What does "zeroth" mean?

In the initial position in a sequence whose elements are numbered starting at zero; the ordinal number corresponding to zero.

What is a synonym for "zeroth"?

Common synonyms include: nothingth, noughth, order zero, zero included, zero order, zero-based.

/ˈzɪɹoʊθ/ adj

adj ·Rare ·Advanced level

Adjective

1
In the initial position in a sequence whose elements are numbered starting at zero; the ordinal number corresponding to zero. not-comparable
"The zeroth order polynomial approximation is constant."
2
Corresponding to a position preceding the first. not-comparable
"A and C are in equilibrium following the Zeroth Law of Thermodynamics."

Adjective

"In my opinion, the fact that we can't easily send the zeroth one should be a reason for us not to try to send and sell the second one."

From zero + -th (ordinal suffix).