This is the 5305th most frequent German word.
bi
"Bi" in German is an informal, shortened form of "bis," meaning "until" or "till."
Here 'bi' occurs as part of the word 'Biologie', which means 'biology'. It pertains to the prefix 'bio-', relating to life.
Biologie hat immer mein größtes Interesse geweckt.
Biology has always sparked my great interest.
In this sentence, 'Bi' is used as a brand name of a ballpoint pen manufacturer, demonstrating proper nouns.
Ich habe einen Bi-Kugelschreiber gekauft.
I bought a Bi-ballpoint pen.
In this context, 'bi' is explained as a prefix meaning 'two', and is often used in compound words to denote duality or a pair.