The word Synoptic as used in science means covering everything, i.e., "the whole picture". The word is related to synopsis, which means roughly the same as abstract or summary, i.e., a description of an entire written work.
Meteorology uses the term synoptic, and astronomy has as well. In meteorology, it means "involving all the Earth", or at least far beyond a single locality, e.g., using data from many locations and modeling the weather over a large region.
In astronomy, it has been used to indicate "including the whole sky", i.e., Celestial Sphere, or much of it. Perhaps it has also been used in other senses.
Large Synoptic Survey Telescope (LSST)