Peaker is a fairly uncommon word that refers to a person who peaks or reaches their highest point. However, there are numerous synonyms that can be used to describe such a person. Some common ones include acme, climax, apex, summit, pinnacle, zenith, top, and highest point. These words all invoke the idea of reaching a peak or pinnacle, whether in terms of achievement, performance, or potential. Other less common alternatives to peaker might include culminating point, crescendo, apogee, or high-water mark. Depending on the context, any of these synonyms could effectively replace the word peaker and convey the same concept in a different way.