In this chapter, unless the context otherwise requires, the following words shall 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 in a savings bank, the board of directors in a co-operative bank and the board of directors in a trust company.
“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.