ballaena — de Vaan
ballaena 'whale' [f. a] (P1.+) According to EM, Greek φάλλωνα, φάλλη 'whale' and Latin ballaena were probably borrowed from a common, unknown source. Leumann 1977, however, thinks that ballaena may have been directly borrowed from Greek, since the Gr. £ formation basium would be regular from an earlier *φαλλων. It remains unclear why Latin wopld have rendered Gr. ph- by means of b-. In any case, the borrowing into … — [de Vaan, s.v. ballaena, p. 82]