Division; separation, as of compound substances.
"The chemical analysis revealed that heat caused a complete departure of the mixture into its individual elements."
In plain English: There is no noun form of depart because it is only used as a verb meaning to leave.
"The sudden depart caused confusion among the passengers waiting at the station."
Usage: This noun form refers to the physical splitting or division of materials and is rarely used in modern everyday language compared to its verb counterpart meaning to leave. You will mostly encounter it in scientific texts describing chemical reactions rather than casual conversation about travel plans.
go away or leave
"The train will depart from platform three in five minutes."
remove oneself from an association with or participation in
"She wants to leave"
"The teenager left home"
"She left her position with the Red Cross"
"He left the Senate after two terms"
"after 20 years with the same company, she pulled up stakes"
To leave.
"The train will depart from station 4 at noon."
The word depart comes from the Old French departir, which originally meant "to divide." It traveled into English with this sense of separation rather than its modern meaning.