WordNet sense 1 (a line of scalp that can be seen when sections of hair are combed in opposite directions):

part

WordNet sense 2 (delivered at the moment of parting as if in flight or retreat):

parthian

WordNet sense 3 (coming after all others in time or space or degree or being the only one remaining):

last

WordNet sense 4 (the act of departing politely):

farewell, leave, leave-taking