sakhi : [m.] a friend. || sākhī (m.), a tree.

A.P. Buddhadatta Mahathera, Concise Pali-English and English-Pali Dictionary [available as digital version from Metta Net, Sri Lanka]

Sakhi [Vedic sakhi m. & f.] a companion, friend; nom. sakhā J ii.29; 348; acc. sakhāraŋ J ii.348; v.509; & sakhaŋ J ii.299; instr. sakhinā J iv.41; abl. sakhārasmā J iii.534; gen. sakhino J vi.478; voc. sakhā J iii.295; nom. pl. sakhā J iii.323; & sakhāro J iii.492; gen. sakhīnaŋ J iii.492; iv.42; & sakhānaŋ J ii.228. In compn with bhū as sakhi˚ & sakhī˚, e. g. sakhibhāva friendship J vi.424; PvA 241; & sakhībhāva J iii.493.

Pali-English Dictionary, TW Rhys Davids, William Stede,

sákhi m. (strong cases, nom. sákhā pl. sákhāyaḥ
• acc. sg. sákhāyam
• gen. abl. sákhyus
• other cases regularly from sakhi) a friend, assistant, companion RV. &c. &c
• the husband of the wife's sister, brother-in-law Gal. ; (ī), f. See below. [Cf. Lat. socius.]

Sanskrit-English Dictionary, by M. Monier William