Complete the series.

ZA144, YB121, XC100, WD81, ?

First letters: Z, Y, X, W move one step backward. Next is V.

Second letters: A, B, C, D move one step forward. Next is E.

Numbers: $144, 121, 100, 81$

$= 12^2, 11^2, 10^2, 9^2$

Next is $8^2 = 64$.

Therefore, the missing term is VE $64$.