No, it's the depth of the situations requiring adult discretion that result in an R rating, not just the language. There's violence, nudity, sexual behavior, drug use and gory scenes to consider as well.
G – General Audiences All ages admitted. This movie contains nothing that would offend parents for viewing by children. Such films may contain only mild fantasy violence or crude humor. Such films have no nudity, sex or drugs of any kind. Alcohol and tobacco may be used in small amounts by adults in the movie, but not by minors, especially in older G rated films. The violence must be cartoonish in nature and/or minimal in quantity.
PG – Parental Guidance Suggested Some material may not be suitable for children. Parents are urged to give parental guidance as the motion picture contains some material that parents might not find suitable for younger children. Such films may contain only mild violence, language, drug references, brief nudity and/or implied or inferred sexual activity.
PG-13 – Parents Strongly Cautioned Some material may be inappropriate for children under 13. Parents are urged to be cautious and contain some material that parents might not find suitable for their pre-teenagers. Such films may contain moderate to strong violence, some suggestive material and nudity, some sexual situations, brief strong language and/or soft drug use.
R – Restricted Under 17 requires an accompanying parent or adult guardian. This movie contains some adult material and parents are urged to learn more about this film before taking their young children with them to see it. Such films may contain rough and/or persistent violence and suggestive material, pervasive language, strong horror, strong crude sexual content, sexually-oriented nudity, and/or hard drug use. Admittance to these films is prohibited for anyone under the age of seventeen unless accompanied by a parent or guardian. Children under 17 or those who do not have ID (including state IDs and drivers' licenses) are not allowed to attend R-rated movies unaccompanied by an adult. In addition, in some theaters, children under 6 cannot see any R-rated films after 6:00 PM.
NC-17 – No One 17 & Under Admitted This film is patently adult and children are not admitted. Such films may contain brutality/pervasive extreme graphic violence, explicit sexual content, sexual assault, extreme horror, sexual language, graphic drug use, and/or aberrational behavior.