Cat litter packaging is full of technical and marketing terms — many of which mean less than they sound, and a few of which matter a great deal for what the litter actually does. This glossary defines the most common terms encountered on bags, in product reviews, and across the rest of this site.
A
Activated carbon (activated charcoal). Carbon that has been processed to have a porous internal structure with very high surface area. It traps odor molecules by physical adsorption rather than masking them with fragrance. Many tofu and crystal litters add small amounts to boost odor control.
Adsorption. A surface process where molecules stick to the outside of a solid material — distinct from absorption, where the substance is taken into the bulk of the material. Activated carbon works by adsorption; absorbent litters like tofu or pine work by absorption.
Aflatoxin. A toxic compound produced by certain molds that can grow on plant-based products including soy, corn, and grain litters when stored in humid conditions. Aflatoxin contamination is the principal reason plant-based litters should be stored in cool, dry, sealed containers.
Agglutinant. A binding agent added to non-clumping bases to produce clumping behavior. Common litter agglutinants include guar gum, corn starch, and sodium bentonite.
Ammonia. The pungent gas produced as urine breaks down. Litter “odor control” is largely about absorbing or neutralizing ammonia before it volatilizes.
B
Bentonite. See sodium bentonite.
Biodegradable. Capable of breaking down through natural processes. Plant-based litters (tofu, pine, corn, walnut, paper) are biodegradable; clay and crystal litters are not. Note that biodegradable does not automatically mean compostable, flushable, or environmentally harmless.
Bottom layer. The litter at the base of the box, below the layer cats actively use. In clumping litters this layer should remain dry and be replaced when the full box is emptied; in non-clumping litters it absorbs urine that passes through the upper layer.
C
Clumping clay. Clay litter containing sodium bentonite, which swells and binds when wet to form a solid clump that can be scooped out. The dominant litter category in North America.
Clumping strength. A loose performance metric for how firm and cohesive a wet clump is. Strong clumps stay intact during scooping; weak clumps crumble back into the box.
Crystalline silica. The mineral form of silicon dioxide that occurs naturally in clay litter. Inhaled crystalline silica dust is classified as a Group 1 carcinogen by the IARC in occupational exposure settings; everyday household exposure is far lower but is the basis for “low-dust” claims on clay packaging. Distinct from silica gel.
Crystal litter. Cat litter made from amorphous silica gel beads. Highly absorbent, low-dust, non-clumping. Sold as “silica” or “crystal” litter.
D
Dust. Fine airborne particles released when litter is poured, walked on, or dug. Sources vary by litter type: clay produces mineral dust, plant-based litters produce organic dust, crystal litter produces little when fresh but more as beads age and crumble.
E
Extrusion. A manufacturing step where soft material is forced through a die under pressure. Tofu litter is typically extruded into pellets; pine pellet litter is also extruded.
F
Flushable. Marketed as safe to dispose of via toilet. Manufacturer flushable claims are widespread but plumbing professionals advise against flushing any cat litter, and California state law (AB 2485) requires warning labels against flushing cat feces due to Toxoplasma risk to marine wildlife. See Can You Flush Tofu Cat Litter? for details.
Fragrance. Scent compounds added to mask litter odor. Common fragrances include floral, baby powder, and citrus. Cats — with roughly 200 million olfactory receptors — are far more sensitive to these scents than humans, and some cats avoid scented litters entirely. Unscented variants exist for nearly every litter type.
G
Granule. A small particle of litter, usually irregular in shape. Distinct from a pellet, which is typically cylindrical and uniform. Granule litters generally clump better but track more.
Guar gum. A plant-derived polysaccharide used as a thickener and binder in food and as an agglutinant in some plant-based litters. Helps tofu litter form firmer clumps.
L
Litter mat. A textured mat placed in front of or under the litter box to catch particles tracked out by the cat. Effective mats use either a deep grid pattern or a two-layer trap design. See Tofu Litter and Tracking.
M
Mineral litter. Cat litter made from naturally occurring minerals — primarily clay (bentonite or fuller’s earth) and silica.
Multi-cat formula. A label on litter products indicating stronger clumping and higher odor-control claims compared to the standard formula. There is no industry-standard definition; the contents differ by manufacturer. See Cat Litter for Multi-Cat Households.
N
N+1 rule. Behavioral guidance for litter box quantity in multi-cat homes: provide one box per cat, plus one additional box. A two-cat home gets three boxes.
Non-clumping. Litter that absorbs liquid without binding into solid clumps. Includes most pine pellet, paper pellet, and crystal litters. Maintenance involves stirring and full replacement on a schedule rather than daily clump removal.
O
Okara. The pulp left over from making tofu or soy milk. The principal ingredient in tofu cat litter. Composed primarily of soybean fiber, with some residual protein and oil. See What Is Tofu Cat Litter?.
P
Pellet. A small, usually cylindrical or rod-shaped piece of compressed litter material. Tofu litter, pine pellet litter, and walnut pellet litter all use this format. Pellets typically track less than granules.
Plant-based litter. Cat litter derived from plant materials — soybean (tofu), wood (pine), corn, wheat, walnut shell, recycled paper. Generally biodegradable and lower in dust than clay.
S
Silica gel. A porous, amorphous form of silicon dioxide with very high water-absorption capacity. The active material in crystal cat litter. Distinct from crystalline silica, the dust associated with clay litter.
Sodium bentonite. A clay mineral that swells substantially when wet — by some estimates up to 15 times its dry volume. The agent that gives clumping clay litter its characteristic firmness. Strip-mined from surface deposits, primarily in Wyoming and South Dakota.
Soybean fiber. The fibrous portion of the soybean left after oil and protein extraction. The bulk material in tofu litter granules.
T
Toxoplasma gondii. A protozoan parasite that completes its life cycle in cats and is shed in cat feces as oocysts. Survives municipal wastewater treatment and standard composting temperatures. The principal reason cat litter and feces should not be flushed or composted into food gardens. Of particular concern for pregnant women, immunocompromised individuals, and marine wildlife.
Tracking. Litter particles that stick to a cat’s paws and fur and scatter outside the box. Affected by particle size, shape, weight, paw fur length, and box design. See Tofu Litter and Tracking.
U
Urine pH. Cat urine is normally slightly acidic. Some “odor-locking” litters work by maintaining a pH that slows ammonia formation in the breakdown of urea.
W
Walnut litter. Cat litter made from ground walnut shells. Naturally dark in color with strong odor-control properties. Less common than clay or tofu but growing in availability.