The day spelled out ( MONDAY)

an interval of 86 400 SI seconds (see second, Systeme International), unless otherwise indicated.

A calendar day unless otherwise specified in the text.

a unique opportunity for JA to reach children a whole school at a time

A calendar day, unless otherwise indicated as "business day" or "school day." Business Day - Monday through Friday, except for Federal and State holidays (unless holidays are specifically included in the designation of business days. School Day - Any day, including a partial day, during the regular school year that students are in attendance at school for instructional purposes.

Means calendar day unless otherwise indicated as school day or business day.

Every day shown on the calendar.

(1) Business Day referring to Monday through Friday, except for Federal and State holidays (unless holidays are specifically included in the designation of business day). (2) School Day referring to any day, including a partial day, that children are in attendance at school for instructional purposes.  The term "school day" has the same meaning for all children in school, including children with and without disabilities.