The Collaborative International Dictionary of English v.0.48:

Quasi \Qua"si\ [L.]
   As if; as though; as it were; in a manner sense or degree;
   having some resemblance to; qualified; -- used as an
   adjective, or a prefix with a noun or an adjective; as, a
   quasi contract, an implied contract, an obligation which has
   arisen from some act, as if from a contract; a quasi
   corporation, a body that has some, but not all, of the
   peculiar attributes of a corporation; a quasi argument, that
   which resembles, or is used as, an argument; quasi
   historical, apparently historical, seeming to be historical.
   [1913 Webster]

WordNet (r) 3.0 (2006):

quasi
    adj 1: having some resemblance; "a quasi success"; "a quasi
           contract"

Moby Thesaurus II by Grady Ward, 1.0:

100 Moby Thesaurus words for "quasi":
   affected, apishly, apocryphal, approximate, approximating,
   approximative, artificial, as it were, assumably, assumed,
   assumedly, assumptively, bastard, bogus, brummagem, byname, close,
   cognominal, colorable, colored, counterfeit, counterfeited,
   diminutive, distorted, dressed up, dummy, embellished, embroidered,
   epithetic, ersatz, factitious, fake, faked, falsified, feigned,
   fictitious, fictive, forged, formal, garbled, hokey, honorific,
   hypocoristic, illegitimate, imitation, imitatively, in name only,
   in seeming, junky, make-believe, man-made, mock, much at one,
   much the same, near, nearly the same, nominal, nominative,
   onomatopoetically, perverted, phony, pinchbeck, plagiarized,
   presumably, presumedly, presumptively, pretended, pseudo, put-on,
   queer, reputedly, same but different, seemingly, self-called,
   self-christened, self-styled, sham, shoddy, simulated, so-called,
   soi-disant, spurious, supposably, supposedly, suppositionally,
   supposititious, supposititiously, synthetic, synthetically, tin,
   tinsel, titivated, titular, twisted, unauthentic, ungenuine,
   unnatural, unreal, warped, would-be



Bouvier's Law Dictionary, Revised 6th Ed (1856):

QUASI. A Latin word in frequent use in the civil law signifying as if,
almost. It marks the resemblance, and supposes a little difference between
two objects. Dig. b. 11, t. 7, 1. 8, Sec. 1. Civilians use the expressions
quasi-contractus, quasi-delictum, quasi-possessio quasi-traditio, &c.