বৈশাখ (Bengali) comes from Sanskrit वैशाख, from Sanskrit विशाखा, from Sanskrit शाखा, from Proto-Indo-Aryan śā́kʰaH, from Proto-Indo-Iranian ćā́kʰaH, from Proto-Indo-European ḱókh₂eh₂ — branch.
বৈশাখ (Bengali): Vaisakha