An interjection is a part of speech that usually has no grammatical connection with the rest of the sentence an simply expresses emotion on the part of the speaker, although most interjections have clear definitions. Filled pauses such as uh, er, um, are also considered interjections. Interjections are generally uninflected function words and have sometimes been seen as sentence-words, because they can replace or be replaced by a whole sentence (they are holophrastic). Sometimes, however, interjections combine with other words to form sentences, but not with finite verbs.