| Acronym | Meaning |
| KBDS | Knowledge-based Design System |
| KBES | Knowledge-based Expert System |
| KCS | K-matrix Centrifugal Sudden (in Mol.-scattering Theory) |
| KDV | Korteweg-de Vries (equation For Solitons) |
| KEDF | Kinetic-energy Density Functional |
| KEGG | Kyoto Encyclopedia Of Genes And Genomes |
| KERD | Kinetic Energy Release Distribution |
| KFM | Kelvin Probe Force Microscopy |
| KFRP | Kevlar Fiber-epoxy Reinforced Plastic |
| KGF | Keratinocyte Growth Factor |
| KHN | Knoop Hardness |
| KHP | Potassium Hydrogen Phthalate |
| KIE | Kinetic Isotope Effect |
| KIMS | Kinetic Interaction Of Microparticles In Solution |
| KIPO | Korean Intellectual Property Office |
| KISS | KPNO International Spectroscopic Survey |
| KKR | Korringa-Kohn-Rostoker (in Band Structure Calcn.) |
| KKR-GF | Korringa-Kohn-Rostoker-Green Function |
| KKRASA | Korringa-Kohn-Rostoker Atomic-sphere Approxn. (in Band Structure) |
| KKRZ | Korringa-Kohn-Rostoker-Ziman (in Energy-band Calcns.) |
| KKT | Kramers-Kronig Transformation |
| KLH | Keyhole Limpet Hemocyanin |
| KLN | Potassium Lithium Niobate |
| KOPRA | Karlsruhe Optimized And Precise Radiative Transfer Algorithm |
| KPLS | Kernel Partial Least Squares |
| KPNO | Kitt Peak National Observatory |
| KRHF | Kramers Restricted Hartree-Fock |
| KRIPES | K-resolved Inverse Photoemission Spectroscopy |
| KRMP2 | Kramers Restricted Moeller-Plesset Second-order (perturbation Theory) |
| KSA | Kirkwood Superposition Approximation |
| KSHV | Kaposi Sarcoma-associated Herpesvirus |
| KSR | Kinase Suppressor Of Ras |
| KSS | Kearns-Sayre Syndrome |
| KST | Max. Vol.-independent Pressure Increase Rate |
| KT | Koopmans Theorem |
| KTFPB | Potassium Tetrakis[3 |
| KTPP | Potassium Tripolyphosphate |
| KVP | Kohn Variational Principle |
| L-CPMET | Linearized Coupled-pair Many-electron Theory |
| L2 | Square Integrable (wave Function) (in Electron-atom Or -mol. Collisions) |
| L2MS | Laser-desorption Laser-ionization Mass Spectrometry |
| L2MS | 2-step Laser Mass Spectrometry |
| LAAFS | Laser Ablation Atomic Fluorescence Spectroscopy |
| LAAM | Levo-alpha Acetyl Methadol |
| LAAS | Laser Atomic Absorption Spectrometry |
| LAB | Linear Alkylbenzene |
| LAC | Liquid Adsorption Chromatography |
| LACBED | Large-angle Convergent-beam Electron Diffraction |
| LACCC | Liquid Absorption Chromatography At Critical Conditions |
| LACE | Laser-assisted Chemical Etching |