The adjective stilted describes something—usually a style of writing or speaking—that is unnaturally formal. It also refers to something raised on stilts, such as some lake houses that are stilted, or resting on stilts over the water.
Imagine someone walking awkwardly on a pair of stilts and you have a good impression of the word stilted — wooden and stiff. Stilt is found in the mid-15th century, referring to walking on wooden stilts across marshy ground. A hundred years later, the word stilted came to refer to the posts holding up a building. It wasn't until 1820 that the word was used as we use it now, to describe writing that does not flow smoothly.