Proto-Indo-European Roots

Root/Stem: *wl.-kw-, *wl.-p-
Meaning:  wolf
Cognates:
Hellenic Greek lukos 'wolf'
Italic Latin lupus 'wolf', vulps, volps 'fox' 
Indic Sanskrit vr.ka- 'wolf'
Iranian Avestan v@hrk 'wolf'
Anatolian Hittite ulippana- 'wolf'
Balkan Albanian ul'k 'wolf'
Germanic Common Germanic *wulfaz 'wolf', *wulg 'she-wolf' >
Gothic wulfs 'wolf', Old Norse ulfr 'wolf', ylgr 'she-wolf', Old English & Old Saxon wulf, Old High German wolf, Middle High German wlpe 'she-wolf'
Baltic Lithuanian vilkas 'wolf', vilpišis 'wild cat', Latvian vilks 'wolf', Sudovian vilkas, Old Prussian wilkis
Slavic Common Slavic *vlk 'wolf' >
Russian volk, Ukrainian vovk, Bulgarian v@lk, Serbo-Croatian vuk, Slovene vlk, Polish wilk, Sorbian wjelk 'wolf'
Notes: Though with different stem elements, the root is still considered to be the same for all IE languages. Its two varieties, with *-kw- and with *-p-, originally had different tints of meaning; it seems that the latter meant 'she-wolf' in Proto-Indo-European. 
As every other common Indo-European term denoting wild animals, this one confirms that the Indo-European homeland was situated in a region where wolfs could be found.