There are myriad synonyms for the word "thumbprints" that one can use to add variation and depth to their writing. Some common alternatives to the word thumbprints include fingerprint, digital impression, handprint, autograph, signature, and imprint. Other possible options include marker, stamp, branding, print, symbol, and identifier. Each of these words carries a slightly different connotation and nuance, and can be used effectively depending on the context. Whether one is writing about forensic science, art, or personal identification, using different synonyms for thumbprints can help one to avoid repetition and keep their writing fresh and engaging.