Mainstayed is spelled as /ˈmeɪnsteɪd/, with the stress on the first syllable. It is a past participle of the verb "mainstay", which means to support or sustain something. The word "mainstay", on the other hand, is spelled with only one "e" and pronounced as /ˈmeɪnsteɪ/. The "ed" ending in "mainstayed" indicates that the action of the verb has already been completed in the past. Therefore, "mainstayed" refers to something that has been supported or sustained in the past.
The word "mainstayed" does not have a distinct etymology because it is not commonly used as a standalone word in English. However, "mainstay" is a noun that originated in Middle English, derived from the combination of the words "main" (meaning "chief" or "principal") and "stay" (referring to a support or prop). The term "mainstay" originated from nautical terminology, describing the strong support or stay that holds the mainmast of a ship in place. Over time, the word has extended its meaning to generally refer to any person or thing providing essential support or stability. The term "mainstayed" could potentially be used as a verb form of "mainstay", but there is no widely accepted usage for it.