1. Not capable of being changed or altered
   - unalterable

See also: final, incurable, last

• family Kasuwonidae
• family Kinosternidae
• family Kyphosidae
• family Labiatae
• family Labridae
• family Lacertidae
• family Lactobacillaceae
• family Lactobacteriaceae
• family Lamiaceae
• family Laminariaceae
• family Lamnidae
• family Lampridae
• family Lampyridae
• family Laniidae
• family Lanthanotidae
• family Lardizabalaceae
• family Laricariidae
• family Laridae
• family Lasiocampidae
• family Latimeridae
• family Lauraceae
• family Lecanoraceae
• family Lecythidaceae
• family Leguminosae
• family Leiopelmatidae