Trivial System : This is the oldest system of naming organic compounds. The trivial name was generally based on the source, some property or some other reason. Quite frequently, the names chosen had Greek or Latin roots.
As given :
(a) Acetic acid derives its name from vinegar of which it is the chief constituent (Latin : acetum = vinegar).
(b) Formic acid was named as it was obtained from red ants. The Greek word for the red ants is formicus.
(c) The names Oxalic acid (oxalus), Malic acid (pyrus malus), Citric acid (citrus) have been derived from botanical sources given in parentheses.
(d) Urea and Uric acid have derived their names from urine in which both are present.
(e) The liquid obtained by the destructive distillation of wood was named as wood spirit. Later on, it was named Methyl alcohol (Greek : methu = spirit; hule = wood).
(f) Names like Glucose (sweet), Pentane (five), Hexane (six), etc. were derived from Greek words describing their properties or structures.
(g) Methane was named as Marsh gas because it was produced in marshes. It was also named as fire damp as it formed explosive mixture with air.