How do I match everything except certain characters using grep?

[indigowinged]

Example textfile used.

$ cat textfile
If the boots fit
boots
bootss

We want to match everything but not the characters bots. The characters in red are the matches. The characters b, o, t, and s are not matched, everything else is.

$ grep -E "[^bots]" textfile
If the boots fit
bootsy was here