First attest; 1696, from botanic (1656), from French botanique or Middle Latin botanicus, from Greek botanikos "of herbs," from botane "a plant, pasture, fodder."
Botany Bay was given that name by Joseph Banks, the famed scientists and botanist who travelled with James Cook between 1768 and 1771. Banks was impressed by all the new species of flora and...
The "a" is pronounced quickly so that it is not "bot-a-ny", but closer to "bot'ny" Bot is pronounced like "bought" in I bought my sister a dress. A is a soft "a". Ny is pronounced like "knee."