Webster's 1913 Dictionary
PROPIONIC
Pro `pi *on "ic, a. Etym: [Proto- + Gr. pi `wn fat. ] (Chem. )
Defn: Pertaining to, derived from, or designating, an organic acid which is produced in the distillation of wood, in the fermentation of various organic substances, as glycerin, calcium lactate, etc. , and is obtained as a colorless liquid having a sharp, pungent odor. Propionic acid is so called because it is the first or lowest member of the fatty acid series whose salts have a fatty feel.
New American Oxford Dictionary
propionic acid
pro pi on ic ac id |ˌprōpēˈänik ˌproʊpiˈɑnɪk ˌæsəd | ▶noun Chemistry a colorless pungent liquid organic acid produced in some forms of fermentation and used for inhibiting the growth of mold in bread. [Alternative name: propanoic acid; chem. formula: C 2 H 5 COOH. ] DERIVATIVES pro pi o nate |ˈprōpēəˌnāt |noun ORIGIN mid 19th cent.: propionic from French propionique, from Greek pro ‘before ’ + piōn ‘fat, ’ it being the first or lowest molecular-weight member of the fatty acid series to form fats.
Oxford Dictionary
propionic acid
propionic acid |ˌprəʊpɪˈɒnɪk | ▶noun [ mass noun ] Chemistry a colourless pungent liquid organic acid produced in some forms of fermentation and used for inhibiting the growth of mould in bread. ●Alternative name: propanoic acid; chem. formula: C 2 H 5 COOH. ORIGIN mid 19th cent.: propionic from French propionique, from Greek pro ‘before ’ + piōn ‘fat ’, it being the first member of the fatty acid series to form fats.
The Wordsmith Dictionary