There are 15 words that start with 'protop'.
| protopod | protopods |
| protoplasm | protoplast |
| protopathic | protophloem |
| protoplanet | protoplasms |
| protoplasts | protophloems |
| protoplanets | protoplasmic |
| protoplanetary | protoporphyrin |
| protoporphyrins | |
Note: These 15 words that start with 'protop' are found from the USA & Canada version of the tournament Scrabble word list.