Definify.com
Webster 1913 Edition
Phthalic
Phthal′ic
,Adj.
[Na
phthal
ene + -ic
.] (Chem.)
Pertaining to, or designating, a dibasic acid obtained by the oxidation of naphthalene and allied substances.
Phthalic acid
(Chem.)
, a white crystalline substance,
C6H4.(CO2H)2
, analogous to benzoic acid, and employed in the brilliant dyestuffs called the phthaleins.