The Proto-Indo-European word *kʷetwóres (m), kʷetwesóres (f), kʷetwōr (n)
Word *kʷetwóres (m), kʷetwesóres (f), kʷetwōr (n)
Meaning four
See also Linear B: to-pe-za ‘table’
Phrygian: *ΔΙΘΥΡ ‘four’
Phrygian: *ΘΙΔΡΑ- ‘four’
Illyrian: *katar ‘four’
Synonyms *kʷetwóres

Comments
Lat. quattuor, Arm. č'ork'/č'ors/č'ors, Alb. katër/katër, Lith. keturi, Ltv. četri, Gaul. petor, Gm. feor/vier, Eng. fēower/four, Gk. tessares, Av. čaθwar, Ir. cethir/ceahair, Kashmiri tsor, Kamviri što, Oscan petora, ON fjórir, Old Prussian keturjāi, Osset. cyppar/cuppar, Pers. /čahār, OCS četyri, Polish cztery, Russ. četyre, Skr. catur, Toch. śtwar/śtwer, Thrac. ketri-, Umbrian petor, Goth. fidwor, Welsh pedwar, Bret. pevar, Lyc. teteri, Kurd. čwar

Other words that might be of interest
*hₓok̂tṓ(u) ‘eight’, *trei- ‘three’, *dwoi- ‘group of two, two’, *h₁oinos ‘one’, *(h₁)néwn̥ ‘nine’, *pénkʷe ‘five’, *sem- ‘one’, *septḿ̥ ‘seven’, *septm̥-k̂ómt-h₂ ‘seventy’, *kswek̂s ‘six’, *tréies (m), trisóres (f), treih₂ (n) tri- [prefix] ‘three’, *dwéh₃(u) ‘two’, *h₁newh₁m̥(h₁néwh₁n̥?) ‘nine’, *tréyes ‘three’, *trī-k̂omt(hₐ) ‘thirty’, *kswek̂s-k̂omt(hₐ) ‘sixty’, *per(hₓ)- ‘first’, *dwiyos~dwitos ‘second’, *h₁newh₁m̥m/n̥-mos ‘ninth’, *hₓok̂towós ‘eighth’, *kswek̂sos ‘sixth’, *kʷturyós~kʷetwortos ‘fourth’, *pn̥kʷtós ‘fifth’, *septm̥-mós ‘seventh’, *triyós ‘third’