Deference was polite respect paid to an individual due to their rank or status.
In 2267, Captain James T. Kirk reintroduced Trelane to Spock, to which he said to the Vulcan, "You do realize, don't you, that it's in deference to the Captain that I brought you here?". Spock then replied, "Affirmative." (TOS: "The Squire of Gothos")