Introduction In sign languages, information is articulated by hands and perceived visually. However, part of the meaning is conveyed by non-manual means, which include eyes, body, and mouth (Bank et al. 248). Mouth actions are the focus of this paper, and researchers distinguish two types of mouth actions: mouth gestures and mouthings. Mouth gestures are mouth actions “inherent in the signed language that may or may not have an independent meaning and that may or may not be lexically bound to a manual sign” (Bank et al. 249). In contrast, mouthings are derived from the spoken language and are lexically bound to a manual sign (Bank et al. 249). This paper aims at exploring both types of mouth morphemes. First, it will describe how mouth gestures are used in three different sign languages: American Sign Language (ASL), Italian Sign Language (LIS), and Sign Language of the Netherlands (NGT). The second point of interest of this paper is to discover how spoken language influences mouth morphemes in these three sign languages. Comparison of Mouth Gestures in ASL, LIS, and NGT Mouth gestures are inherent in sign language and do not originate in the surrounding spoken language. Therefore, this type of mouth action involves “various configurations of the jaw, lips, cheeks and tongue and imply some air movement or ‘noises’” (Fontana 106). The role of mouth gestures is threefold. First, they can serve to distinguish between two manual homonyms. For example, in LIS, the words “impossible” and “dead” are distinguished only by the presence of the mouth morpheme (puffed cheek and the release of air) in the word “impossible” (Fontana 107). Another function of mouth gestures is adverbial or adjectival. For example, in ASL, the mouth morpheme “clench” means “extremely” and is used to modify the adjectives shown as manual signs (Bickford and Fraychineaud 40). It implies that the manual sign “clean” combined with the mouth morpheme “clench” would mean “extremely clean.” The third function of mouth gestures is expressive and can be compared to manual gestures made by people using the spoken language (Fontana 118). Sandler found out that signers of different sign languages used mouth gestures in similar expressive ways when retelling the cartoon that they were shown (253). For instance, they tried to convey the vibrations that they felt at the moments when a hearing person would hear a sound. Thus, mouth gestures perform similar functions in various sign languages. Some mouth gestures seem to be similar in various languages but convey a different meaning. For example, pursed lips in ASL mean “to an amazing degree” and “to a small degree,” while in NGT, this mouth morpheme means “at ease” (Bickford and Fraychineaud 44). However, there are also some similarities in the meaning of mouth gestures. For example, clenched teeth in both ASL and LIS may mean “fast” or “immediate” (Bickford and Fraychineaud 41; Branchini and Mantovan 163). Sometimes, mouth gestures reflect the surrounding culture. For example, in LIS, signers use the mouth morpheme “tp,” which is shown as the protrusion of the tongue and means “like not” (Branchini and Mantovan 163). This morpheme reflects Italians’ habit of sticking out their tongue when they do not like something (Branchini and Mantovan 163). Likewise, in ASL, “pow” is used by both signers and English speake