See distinctly (with the eyes or the mind); distinguish (an object or fact); discern.
transferred sense
Decree a person etc. to be or to do something by judicial sentence. (in the phrase “to decern in”, obsolete) To mulct in by decree of court.
Decree by judicial sentence that something be done.
intransitive
with simple object
To notice or view, especially carefully or with attention to detail.
To take note of and celebrate (a holiday or similar occurrence); to follow (a type of time or calendar reckoning).
To comment on something; to make an observation.
To follow or obey the custom, practice, or rules (especially of a religion).