Free from loss, especially not losing electrical energy or force(adjective)
Not losing information.(adjective)
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Use "lossless" in a sentence
"Rip in lossless format like Flac or Apple Lossless (with iTunes) then give away to charity."
"Archival images are in: resolution of 300 dpi, minimum bit depth of 8 (256 colors/grayscale), uncompressed format or in lossless compression format."
"The sharp increase in bitrate falls in line with what's known as lossless compression, meaning bit-for-bit replication of the source material in a single file."