# Supernumerariness

What word goes in the box with the question mark?

The word is

AXIS.

Because:

Each of these is an anagram of a number plus a single extra letter:
FORUM = FOUR + M
WAVELET = TWELVE + A
EXIGENTS = SIXTEEN + G
ENVIES = SEVEN + I
ETCHER = THREE + C

It turns out that

there's only one way to fill in the remaining numbers from 1 to 16 to create a magic square (that is, a square where all the rows, columns, and diagonals sum to the same number). That solution is:

05 13 04 12
16 08 01 09
02 10 15 07
11 03 14 06
And the only word that is an anagram of SIX plus an extra letter is AXIS.

• You literally just pipped me to this! Got most of the way through my write-up... Well done. A good solve to a good puzzle :) (EDIT: You may want to point out explicitly how you jump from your 2nd to your 3rd spoiler, thanks to the spelled-out word...)
– Stiv
Sep 21 '21 at 20:19
• I wonder what words go into the other boxes...
– Stef
Sep 22 '21 at 13:36