Building on the recognition of the Luwian stem /watt(i)-/ ‘mountain’ and its derivatives wattatar ‘mountain sculpture’ and wattant(i)- ‘mountain-shaped (?)’ (by Hawkins, Gérard, and Goedegbuure), the word family can be enlarged by two putative derivatives, i.e. wattann(i)- ‘little mountain’ and wattatt(i)-/wattatt(a)- ‘hill country (?)’ (following Yakubovich). Regarding the etymology, the present article suggests a ‘root’ connection with the local particle *ud ‘up(ward), forth’ (cf. Ved. úd ‘id.’, Gk. ὕστερος ‘hindmost, last’ und Lith. ùž ‘up(ward), behind’). In terms of stem formation, Luw. /watt(i)-/ represents a vṛddhi derivative *wéd-o- (type nu ‘now’ → néu̯ -o- ‘new’), which changed to the attested form by Čop’s Law in Luwian (*é + lenis consonant > á + fortis consonant). The derivation seems to be contradicted by the change *e > i / u̯ _alveolar, but examples for this change are rare in Luwian. As for the root ḫwid- where the expected change according to the Čop’s Law is not attested, it is argued that only a few forms of ḫwidar ‘wild animal’ or its derivatives were in fact subject to the Čop’s Law, whereas in other forms either the root vowel was followed by double consonants (-dn- or -dw-) or the accent did not fall on the root (e.g. ḫu-i-d/ta-a-ar, ḫwidnaima/i-, ḫwidumnāḫi(t)-, ḫwidwāl(i)-). Consequently, the forms not affected by Čop’s Law could have been generalized. The second counterexample, winal- ‘stick, staff’, is argued to be of a secondary nature (root win- < * gʷʰen- in unknown context, plus suffix -al- < * -lo-). Therefore, nothing speaks against the suggested derivation of Luw. /watt(i)-/ from *u̯ éd-o-. Possibly, also the root *u̯ ed- ‘water’ can be connected with the same root (cf. Eng. spring ‘source’ und to spring ‘to jump (upward)’.