1. A blended word, derived from the phrase "botanical dictionary".
2. A reference containing an alphabetical list of 21,261 botanical words, with information given for each word, usually including the etymology (i.e., history and/or origin) and pronunciation.
Almost 250 years ago, the Swedish botanist Carl von Linn� published Species Plantarum and binomial nomenclature was born. This systematic approach to naming plants (and animals) is still the universally-recognized system used today. While many gardeners struggle with "Latin names" of plants, knowing a plant's botanical name allows you to converse with gardeners all over the world.
Here you can look up a plant name, discover its meaning and find a guide to pronouncing it. But take it from W.T. Stearn, an authority on the subject: "Botanical Latin is essentially a written language .... How they are pronounced really matters little provided they sound pleasant and are understood by all concerned..."
If you were looking for a gardening term (but not necessarily a plant name) try Gardenology, the Dave's Garden knowledge base of gardening terminology.