The background relating to the question and some of the answers are in CS25 (FAR25); also see part 23 for the smaller aircraft.
CS 25.773 Pilot compartment view.
(b) (2) No single failure of the systems used to provide the view required … must cause the loss of that view by both pilots in the specified conditions.
(3) The first pilot must have –
(i) A window that is openable under the conditions … when the cabin is not pressurised, … or
(ii) An alternative means to maintain a clear view under the conditions.
(4) The openable window specified in sub-paragraph (b)(3) of this paragraph need not be provided if it is shown that an area of the transparent surface will remain clear sufficient for at least one pilot to land the aeroplane safely in the event of - … …
CS 25.775 Windshields and windows
(e) The windshield panels in front of the pilots must be arranged so that, assuming the loss of vision through any one panel, one or more panels remain available for use by a pilot seated at a pilot station to permit continued safe flight and landing.
I suspect that many years ago the conditions which caused a loss of view were associated with storms, ice etc; thus the term ‘storm window’. The regulations in those days might have even used the term.
More recently the window was known as a 'direct view' or 'clear vision' window, and even more recently, particularly when 773 (4) is used, then the term 'escape' window may be used.