Question

How did the meaning of "organic" change during the 19th century?

Answer 1

More than `200` years ago, it was thought that only living and non-living things can make "organic" molecules. Early chemist never succeed in synthesizing organic compounds and their failure led them to believe that organic compounds can't be synthesized from inorganic or non-living material . The idea supports vital force theory which states:
"A vital force is required to synthesize organic molecules and this vital force is not present in inorganic substances"

However, On the onset of `19century` (in 1828) this theory was rejected by Friedrick Wohler when he obtained urea `(NH_2)_2CO`, an organic compound from ammonium cyanate`NH_4CNO`, an inorganic salt.

This discovery led to the synthesis of million of organic compounds.

And now "Organic" compound means the hydrocarbon or its derivatives. However, carbon is considered a most essential or basic element of organic compounds.

`Note:`
Carbon is the only element in the Periodic Table that is capable of forming endless bonds with itself (Concatenation). That is why Carbon can form very complicated molecules with itself like the Steroids, Triglycerides, Enzymes, Plastics etc...