Pal
late 17th century: from Romani, ‘brother, mate’, based on Sanskrit bhrātṛ ‘brother’.
wiktionary
Borrowed from Angloromani pal(“brother, friend”), from Romani phral(“brother”), from Sanskrit भ्रातृ(bhrātṛ, “brother”). Doublet of brother and frater.
etymonline
pal (n.)
"partner, mate, chum," slang, 1680s, said to be from Romany (English Gypsy) pal "brother, comrade," a variant of continental Romany pral, plal, phral, which are probably from Sanskrit bhrata "brother" (from PIE root *bhrater- "brother"). Colloquial extended form palsy-walsy is attested from 1930. Pally (adj.) is attested by 1895.
pal (v.)
"behave as pals; spend time or pursue activities together," 1879, from pal (n.). Originally with in; by 1889 with up; 1915 with round or around. Related: Palled; palling.