Section 1. As used in this chapter, the following words shall, unless the context clearly requires otherwise, have the following meanings:?
''Bank'', a savings bank, co-operative bank or trust company incorporated as such in the commonwealth.
''Board'', the board of trustees or directors of a bank.
''Commissioner'', the commissioner of banks.
''Federally-chartered bank'', a national bank association, a federal savings and loan association, a federal savings bank or a federal credit union authorized to do business in the commonwealth.