Synthetic means made by people rather than occurring naturally. A synthetic fabric like polyester is manufactured in a factory from chemicals, while cotton grows on plants. Synthetic rubber comes from petroleum products, while natural rubber comes from rubber trees.

Scientists create synthetic materials to have specific properties that natural ones might lack. Synthetic diamonds can be grown in laboratories and look identical to mined diamonds. Synthetic vitamins manufactured in factories work the same way in your body as vitamins from food. Some synthetic materials are cheaper to produce, more durable, or more consistent than their natural counterparts.

The word can also describe something that feels artificial or forced rather than genuine. A synthetic smile looks fake, and a synthetic compliment sounds insincere. When someone's enthusiasm feels synthetic, you sense they're pretending rather than expressing real emotion.

In chemistry and manufacturing, synthetic simply describes human creation without any negative judgment. Your winter jacket might contain synthetic insulation that keeps you warmer than natural materials could. But when describing feelings or relationships, calling something synthetic usually means it lacks authenticity or warmth.