Boston is a city, and does not really have an abbreviation. However, for it could possibly be written as "Bos" if an abbreviation is needed.
In medicine, the abbreviation PRN is used. It is from Latin "pro re nata" meaning for an occasion that has arisen, as circumstances require, as needed.
PRN
The abbreviation of "legendary" is often represented as "legend." However, in contexts where an abbreviation is specifically needed, it may also be shortened to "leg."
No
There is no standard abbreviation in English for "cousins," because the word is so short that no abbreviation is usually needed.
I don't believe that there is an abbreviation for Chicago.
RES is the abbreviation for resource. A resource is a source of supply, support, or aid, especially one that can be readily drawn upon when needed.
The abbreviation for decameter is "dam", since the abbreviation of deka is da and the abbreviation of meter is m.
PRN does not do anything to a patient. It is a medical abbreviation that means "as needed". A medication or treatment ordered as PRN means to give it as needed.
Two inhalations every 6 (hours) or as needed.
AW is not a recognised abbreviation so more information is needed, like what kind of appliance it is.