What does lossy mean?
Lossy describes a process or format that reduces information and cannot perfectly restore every detail of the original. The term is most familiar in computing: lossy compression makes files smaller by discarding data deemed unnecessary or less important to human perception, as many JPEG images and MP3 audio files do. This saves storage space and can reduce the time needed to transmit or load a file, but it may permanently reduce quality. The adjective can also refer more generally to any process that diminishes precision or fidelity. Its opposite is lossless, which preserves all the original data and permits exact reconstruction. Consequently, lossy is often a practical choice for images, video, and sound distributed online, while lossless formats are preferred when exact reproduction is essential.
adjectiveInvolving or causing a loss, especially the irreversible loss or distortion of information in digital compression. It may also describe a process that reduces quality or fidelity.
- Involving the loss or distortion of information, especially in digital compression.
- Involving a reduction in quality, fidelity, or precision.
"The designer exported the illustration as a lossy JPEG because the smaller file was easier to publish."
"Lossy compression greatly reduced the size of the audio file."
"Repeated copying produced a lossy image with noticeably less detail."
Lossy compression makes digital files smaller by discarding some of the original information—a useful trade-off, but one that cannot always be undone.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does lossy come from?
Lossy is a modern English formation built from the noun loss and the suffix -y, meaning “accompanied by or tending toward loss.” Its semantic base is English loss, which is related to lose and lost. The adjective became especially prominent with the development of digital data compression in the twentieth century, when formats that reduced file size at the expense of some original information required a concise contrasting label.
Related word forms
How lossy is actually used
The term is most common in computing, digital imaging, audio processing, and data storage. In these contexts it contrasts with lossless processing, which preserves the original information exactly.