Q: Is a thesis considered a publication?

The question ‘Is a thesis considered a publication?’ admits of no simple answer. However, to begin with, I assume here that typically, in the context of higher education in the United States, a ‘thesis’ – as opposed to a ‘dissertation’ –implies an argument based on existing research and is usually a requirement for a master’s degree whereas a dissertation requires its author to undertake original research and discuss its implications and is usually a requirement for a doctorate (PhD). Note that in the UK, it is often the other way around.  

Next, take ‘considered’: considered by whom? The author of the thesis and the educational institution to which the thesis is submitted will certainly consider the thesis a publication, but if we assume ‘publication’ to be synonymous with ‘making public’, the matter becomes less clear-cut. (According to the Oxford dictionaries, a publication is ‘a book or journal issued for public sale’.) If the thesis is available to anyone, whether gratis or on payment, it can be considered a publication; if access to a thesis is restricted irrespective of payment, it would be inappropriate to designate it as a publication. 

To sum up, the question can be answered only in the context of a specific situation, such as candidature for an academic appointment.