The phrase "was prolific" implies that someone has been highly productive in their work or creative output. Some synonyms for "was prolific" could be "prolifically productive," "prolifically creative," "copious," "abundant," "productive," "efficient," or "fruitful." Other words that convey a similar meaning of productivity include "proliferative," "generative," "fecund," "plentiful," and "prolifically talented." These terms can be used to describe prolific writers, artists, musicians, or any individual who has demonstrated a high level of productivity in their chosen field. Overall, these synonyms offer a more precise and specific way of conveying the meaning of "was prolific".