The word "doodah" is an informal and slang term used to describe something whose name you may not remember, or something whose name you don't know. There are a variety of synonyms for the word "doodah." One of the most commonly used synonyms is "thingamabob," which is also an informal term used to refer to something whose name you cannot remember. Another popular synonym for "doodah" is "whatchamacallit," which is another term that can be used when you forget the name of something. Some other synonyms for "doodah" include "gadget," "widget," "doohickey," and "contraption".