From a- + Middle English loof (="weather gage," also "windward direction"), probably from Dutch loef (="the weather side of a ship"); originally a nautical order to keep the ship's head to the wind, thus to stay clear of a lee-shore or some other quarter, hence the figurative sense of "at a distance, apart" 
- At or from a distance, but within view, or at a small distance; apart; away.
1922, Ben Travers, chapter 2, A Cuckoo in the Nest:
- Mother […] considered that the exclusiveness of Peter's circle was due not to its distinction, but to the fact that it was an inner Babylon of prodigality and whoredom, from which every Kensingtonian held aloof, except on the conventional tip-and-run excursions in pursuit of shopping, tea and theatres.
- Without sympathy; unfavorably.
1832, Isaac Taylor, Saturday evening, page 363:
- But to open the Bible in this spirit — to take the Book as from the hand of God, and then to look at it aloof, and with caution, as if throughout it were illusory and enigmatical, is the worst of all impieties.
- See also Wikisaurus:arrogant
- (obsolete) away from; clear of
- Rivetus […] would fain work himself aloof these rocks and quicksands.
Part or all of this entry has been imported from the 1913 edition of Webster’s Dictionary, which is now free of copyright and hence in the public domain. The imported definitions may be significantly out of date, and any more recent senses may be completely missing.