It would seem "MOTD" == "Message of the Day"

serf a day ago | parent [-]

since pre-unix MIT time-sharing machines in the mid 60s.

probably before then somewhere on some physical bulletin board somewhre.

	▲	Computer0 a day ago \| parent [-]
		Everyday new HN users become more removed from the mid 60's and the relevance of the concept of a MOTD. I think a definition is worthy of being considered as 'additive' to the conversation.