Going from Tajik to Azerbaijani (Azษrbaycan) has a composite linguistic distance of 85% (heuristic estimate). Below is the dimension-by-dimension breakdown.
Shared vocabulary, cognates, and loanwords.
Morphology, syntax, word order, cases.
Shared sounds and phoneme inventory.
Cyrillic โ Latin
Indo-European โ Turkic
The 5 languages with the lowest linguistic distance from Tajik:
A quick 3-question check between Tajik and Azerbaijani. No signup.