| Term (Isoline) | Meaning / Definition | Commonly Used For / Example |
| Isobath | Line joining places of equal depth in oceans, seas or lakes. | Oceanography, Nautical Charts |
| Isobar | Line joining places of equal atmospheric pressure. | Weather Maps |
| Isohypses (Contour Lines) | Line joining places of equal elevation (height above Mean Sea Level). | Topographic Maps |
| Isohyet | Line joining places receiving equal rainfall during a given period. | Climatology |
| Isohaline (Isohaline Line) | Line joining places of equal salinity in oceans or seas. | Oceanography |
| Isotherm | Line joining places having equal temperature. | Climate Maps |
| Isohel | Line joining places receiving equal duration/intensity of sunshine (solar radiation). | Meteorology |
| Isopleth | General term for a line joining places having equal values of any geographical phenomenon (e.g., rainfall, temperature, population density). | Geography & Statistics |
| Isochrone | Line joining places requiring equal travel time from a given point. | Transport Geography |
| Isotach | Line joining places of equal wind speed. | Meteorology |
| Isogon (Isogonic Line) | Line joining places of equal magnetic declination. | Navigation |
| Agonic Line | Line joining places with zero magnetic declination. | Geomagnetism |
| Isoclinic Line | Line joining places of equal magnetic dip (inclination). | Geophysics |
| Isodynamic Line | Line joining places of equal magnetic field intensity. | Geomagnetism |
| Isoseismal Line | Line joining places experiencing equal earthquake intensity. | Seismology |
| Coseismal Line | Line joining places where an earthquake is felt at the same time. | Earthquake Studies |
| Isoneph | Line joining places of equal cloud cover. | Meteorology |
| Isohume | Line joining places of equal humidity. | Climatology |
| Isopectic Line | Line joining places having equal duration of ice cover/freezing. | Polar Geography |
| Isobront | Line joining places experiencing thunderstorms at the same time. | Meteorology |
| Isodose | Line joining places receiving equal radiation dose. | Environmental Studies |
| Isopycnal | Line joining places of equal density (especially seawater). | Oceanography |
| Isogonic Line | Another name for Isogon (equal magnetic declination). | Navigation |
