Correct spelling for the English word "tideday" is [tˈa͡ɪdde͡ɪ], [tˈaɪddeɪ], [t_ˈaɪ_d_d_eɪ] (IPA phonetic alphabet).
I apologize, but I couldn't find any information or widely recognized definition for the term "tideday" in any reputable dictionaries or sources. It is possible that "tideday" may be a rare or obscure term, a regional variation, or perhaps a specific term used in a specialized field or industry that is not widely known to the general public.
If "tideday" is a term that is specific to a particular context or domain, it would be helpful to provide more context or information about its usage so that I can better assist you in providing a definition or explanation. Without further information or clarification, it is difficult to provide an accurate definition for a term that does not have a widely recognized meaning.