What does Tashbeeh mean?

The correct definition of tashbeeh (anthropomorphism) according to Ahl-us-Sunnah is what Imaam at-Tirmidhee narrated from Imaam Ishaaq ibn Raahawaih:

Tashbeeh is to say that Allah is like this or that, or resembles this or that.

For the full text, see: Jaami‘-ut-Tirmidhee [1]

In other words, merely affirming an attribute that is common to both Creator and creation does not constitute tashbeeh unless one uses words such as “like,” “resemble,” “similar” and so on.

Imaam Ishaaq was a close companion and colleague of Imaam Ahmad, a scholar of Hadeeth and the Imaam of an independent Fiqh madhhab.

A similar definition was stated by many other imaams including Ahmad ibn Hambal[2] and adh-Dhahabee [3].

And Allah knows best.

References:

[1] 2/116-117, Darussalam English edition

[2] C.f. Al-Ibaanah, 3/325 by Ibn Battah

[3] Al-Arba‘een fee Sifaat Rabb-il-‘Aalameen, 1/104