Bulbasaur

The English name for Bulbasaur is made up by joining bulb and saur.

The word bulb is originally from Latin bulbus or Greek bolbós. Interestingly, the dictionary entry of bulb contains numerous definitions of which botany and anatomy are both relevant.

Botany. a usually subterranean and often globular bud having fleshy leaves emergent at the top and a stem reduced to a flat disk, rooting from the underside, as in the onion.

Anatomy. any of various small, bulb-shaped structures or protuberances

Next up, the suffix saur is pretty self-explanatory and originates from the Greek word saûros meaning lizard.

Combining both meanings, Bulbasaur in English means "a lizard with a globular protuberance with fleshy leaves". That sounds like our faithful Bulbasaur all right.

Based on research, I've found that Bulbasaur's Japanese name is layered in meaning - a bit like an onion. The official Pokédex entry is in Katakana フシギダネ (fushigidane) but can be translated to Hiragana as ふしぎだね.

The Hiragana ふしぎ (fushigi) translates to strange, wonderful, amazing, curious, and mysterious​.

If we take the unmodified version of だ we have たね (tane). This translates to seed which fits perfectly with Bulbasaur as the Seed Pokémon. Why did they use だね (dane) instead? The best I could find is that だね is used to create a rhetorical question as it adds "isn't it?" to the end of the sentence. For example "Squirtle is the best starter, isn't it?" is rhetorical and definitely doesn't expect a response since both speaker and listener obviously agree.

Taking all of that together, Bulbasaur has the most likely meaning of "Strange seed, isn't it?". And it is a most strange, wonderful and mysterious seed indeed.