1.  sir(n = noun.person) - term of address for a man;
is a kind of adult male, man

2.  sir(n = noun.person) - a title used before the name of knight or baronet;
is a kind of male aristocrat

1.  A man of social authority and dignity; a lord; a master; a gentleman; -- in this sense usually spelled sire. [1913 Webster]
"He was crowned lord and sire." [1913 Webster]
"In the election of a sir so rare." [1913 Webster]

2.  A title prefixed to the Christian name of a knight or a baronet. [1913 Webster]
"Sir Horace Vere, his brother, was the principal in the active part." [1913 Webster]

3.  An English rendering of the LAtin Dominus, the academical title of a bachelor of arts; -- formerly colloquially, and sometimes contemptuously, applied to the clergy. Nares. [1913 Webster]
"Instead of a faithful and painful teacher, they hire a Sir John, which hath better skill in playing at tables, or in keeping of a garden, than in God's word." [1913 Webster]

4.  A respectful title, used in addressing a man, without being prefixed to his name; -- used especially in speaking to elders or superiors; sometimes, also, used in the way of emphatic formality. Sheridan. [1913 Webster]
" Anciently, this title, was often used when a person was addressed as a man holding a certain office, or following a certain business. “Sir man of law.” “Sir parish priest.”" Chaucer. [1913 Webster]

sir, n.
1 a polite or respectful form of address or mode of reference to a man.
2 (Sir) a titular prefix to the forename of a knight or baronet.

Etymology:
ME, reduced form of SIRE

N  title, honor, knighthood, highness, excellency, grace, lordship, worship, reverence, reverend, esquire, sir, master, Mr, signor, senor, Mein Herr, mynheer, your honor, his honor, serene highness, handle to one's name, decoration, laurel, palm, wreath, garland, bays, medal, ribbon, riband, blue ribbon, cordon, cross, crown, coronet, star, garter, feather, feather in one's cap, epaulet, epaulette, colors, cockade, livery, order, arms, shield, scutcheon, reward.

N  man, male, he, him, manhood, gentleman, sir, master, sahib, yeoman, wight, swain, fellow, blade, beau, elf, chap, gaffer, good man, husband, Mr, mister, boy, cock, drake, gander, dog, boar, stag, hart, buck, horse, entire horse, stallion, gibcat, tomcat, he goat, Billy goat, ram, tup, bull, bullock, capon, ox, gelding, steer, stot, androgen, homosexual, gay, queen, male, he-, masculine, manly, virile, unwomanly, unfeminine, Pron, he, him, his, hominem pagina nostra sapit, homo homini aut deus aut lupus, homo vitae commodatus non donatus est.

sir alan lloyd hodgkin, sir alec guinness, sir alexander fleming, sir alexander korda, sir alexander mackenzie, sir alexander robertus todd, sir alfred charles bernard lovell, sir alfred hitchcock, sir angus wilson, sir anthony hopkins, sir anthony philip hopkins, sir anthony vandyke, sir arthur conan doyle, sir arthur john evans, sir arthur stanley eddington, sir arthur sullivan, sir arthur travers harris, sir barton, sir bernanrd williams, sir bernard law montgomery, sir bernard lovell, sir charles leonard woolley, sir charles scott sherrington, sir charles spencer chaplin, sir charles wheatstone, sir charles william siemens, sir christopher wren, sir clive marles sinclair, sir david alexander cecil low, sir david bruce, sir david low, sir edmund hillary, sir edmund percival hillary, sir edward elgar, sir edward victor appleton, sir edward william elgar, sir edwin landseer luytens, sir edwin lutyens, sir ernst boris chain, sir francis bacon, sir francis drake, sir francis galton, sir frank whittle, sir fred hoyle, sir frederick ashton, sir frederick gowland hopkins, sir frederick grant banting, sir frederick william herschel, sir galahad, sir gawain, sir geoffrey wilkinson, sir george otto trevelyan, sir george paget thomson, sir geraint, sir hans adolf krebs, sir harold george nicolson, sir harold walter kroto, sir harry maclennan lauder, sir henry bessemer, sir henry joseph wood, sir henry maxmilian beerbohm, sir henry morgan, sir henry morton stanley, sir henry percy, sir henry rider haggard, sir henry wood, sir herbert beerbohm tree, sir hiram stevens maxim, sir howard walter florey, sir humphrey davy, sir humphrey gilbert, sir isaac newton, sir isaac pitman, sir jack hobbs, sir jacob epstein, sir james augustus henry murray, sir james augustus murray, sir james clark ross, sir james dewar, sir james george frazer, sir james matthew barrie, sir james murray, sir james paget, sir james paul mccartney, sir james young simpson, sir john carew eccles, sir john cockcroft, sir john cowdery kendrew, sir john douglas cockcroft, sir john everett millais, sir john falstaff, sir john frederick william herschel, sir john gielgud, sir john hawkins, sir john hawkyns, sir john herschel, sir john ross, sir john suckling, sir john tenniel, sir john vanbrigh, sir joseph banks, sir joseph john thomson, sir joseph paxton, sir joshua reynolds, sir lancelot, sir laurence kerr olivier, sir leonard hutton, sir leonard woolley, sir leslie stephen, sir martin frobisher, sir matthew flinders, sir mortimer wheeler, sir noel pierce coward, sir oliver joseph lodge, sir oliver lodge, sir patrick manson, sir paul gavrilovich vinogradoff, sir peter brian medawar, sir peter paul rubens, sir peter ustinov, sir philip sidney, sir rabindranath tagore, sir ralph david richardson, sir rex harrison, sir richard burton, sir richard francis burton, sir richard owen, sir richrd steele, sir robert eric mortimer wheeler, sir robert peel, sir robert robinson, sir robert walpole, sir roger gilbert bannister, sir ronald ross, sir sarvepalli radhakrishnan, sir seretse khama, sir stephen harold spender, sir terence mervyn rattigan, sir thomas gresham, sir thomas lawrence, sir thomas malory, sir thomas more, sir thomas raffles, sir thomas stamford raffles, sir thomas wyat, sir thomas wyatt, sir tim rice, sir tom stoppard, sir walter norman haworth, sir walter ralegh, sir walter raleigh, sir walter scott, sir william alexander craigie, sir william chambers, sir william crookes, sir william gerald golding, sir william gilbert, sir william herschel, sir william huggins, sir william rowan hamilton, sir william turner walton, sir william wallace, sir william walton, sir winston leonard spenser churchill, sir yehudi menuhin