1. allowing some substances to pass through but not others
Usage: scientific; biology; chemistry

Examples

• The cell membrane is semipermeable, allowing water to enter but blocking larger molecules.
• Semipermeable membranes are used in water filtration systems.
• The dialysis machine uses a semipermeable barrier to remove waste from blood.
• Plant roots have semipermeable walls that control nutrient absorption.
• The semipermeable plastic allows air to pass through while keeping moisture out.
• Scientists study how semipermeable materials can separate different chemicals.