Going from Khmer to Italian (Italiano) has a composite linguistic distance of 83% (heuristic estimate). Below is the dimension-by-dimension breakdown.
Shared vocabulary, cognates, and loanwords.
Morphology, syntax, word order, cases.
Shared sounds and phoneme inventory.
Khmer → Latin
Austroasiatic ↔ Indo-European
The 5 languages with the lowest linguistic distance from Khmer:
A quick 3-question check between Khmer and Italian. No signup.