a locket (chained ornament)

registration / a record or entry / (Internet) a subscription on a platform like YouTube

to register / to record an entry / (Internet) to subscribe on a platform like YouTube

thesis; dissertation; article

Los Angeles (a census-designated place in Willacy County, Texas, United States) / Los Angeles River (a river in California, United States) / Los Angeles (a large city in California, United States)

a rib (curved bone)

robotics

six-chambered (revolver), six-shooter

(mathematics) topology (study of geometric properties that are not changed by stretching etc.)

(music) rock (style of music) / on the rocks (served over ice)