1.  sweetheart(n = noun.person) steady, sweetie, truelove - a person loved by another person;
is a kind of lover
has particulars: dulcinea, ladylove, sugar daddy, valentine

2.  sweetheart(n = noun.person) - any well-liked individual; "he's a sweetheart"
is a kind of good person

3.  sweetheart(n = noun.person) beauty, dish, knockout, looker, lulu, mantrap, peach, ravisher, smasher, stunner - a very attractive or seductive looking woman;
is a kind of adult female, woman

   sweetheart(s = adj.all) - privileged treatment of a favored person or corporation (sometimes unethically); "another sweetheart deal based on political influence"

   A lover of mistress. [1913 Webster]

sweetheart, n.
1 a lover or darling.
2 a term of endearment (esp. as a form of address).

Idiom:
sweetheart agreement (or deal) colloq. an industrial agreement reached privately by employers and trade unions in their own interests.

N  love, fondness, liking, inclination, regard, dilection, admiration, fancy, affection, sympathy, fellow-feeling, tenderness, heart, brotherly love, benevolence, attachment, yearning, eros, tender passion, amour, gyneolatry, gallantry, passion, flame, devotion, fervor, enthusiasm, transport of love, rapture, enchantment, infatuation, adoration, idolatry, Cupid, Venus, myrtle, true lover's knot, love token, love suit, love affair, love tale, love story, the, old story, plighted love, courtship, amourette, free love, maternal love, storge, parental love, young love, puppy love, attractiveness, popularity, favorite, lover, suitor, follower, admirer, adorer, wooer, amoret, beau, sweetheart, inamorato, swain, young man, flame, love, truelove, leman, Lothario, gallant, paramour, amoroso, cavaliere servente, captive, cicisbeo, caro sposo, inamorata, ladylove, idol, darling, duck, Dulcinea, angel, goddess, cara sposa, betrothed, affianced, fiancee, flirt, coquette, amorette, pair of turtledoves, abode of love, agapemone, loving, fond of, taken with, struck with, smitten, bitten, attached to, wedded to, enamored, charmed, in love, love-sick, over head and ears in love, head over heels in love, affectionate, tender, sweet upon, sympathetic, loving, amorous, amatory, fond, erotic, uxorious, ardent, passionate, rapturous, devoted, motherly, loved, beloved well beloved, dearly beloved, dear, precious, darling, pet, little, favorite, popular, congenial, after one's mind, after one's taste, after one's fancy, after one's own heart, to one's mind, to one's taste, to one's fancy, to one's own heart, in one's good graces, dear as the apple of one's eye, nearest to one's heart, lovable, adorable, lovely, sweet, attractive, seductive, winning, charming, engaging, interesting, enchanting, captivating, fascinating, bewitching, amiable, like an angel, amantes amentes, credula res amor est, militat omnis amasius, love conquers all, omnia vincit amor, si vis amari ama, the sweetest joy, the wildest woe.

N  favorite, pet, cosset, minion, idol, jewel, spoiled child, enfant gat_e, led captain, crony, fondling, apple of one's eye, man after one's own heart, persona grata, love dear, darling, duck, duckey, honey, sugar, jewel, mopsey, moppet, princess, sweetheart, sweetie, teacher's pet, general favorite, universal favorite, idol of the people.