Etymology Map
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Penicillin

3 stages from Latin to English.

Today it means an antibiotic produced from Penicillium moulds

Where does the word "penicillin" come from? It comes from Latin penicillus, passing through New Latin before entering English (1929).

1
Stage 1 of 3
penicillus
Latin · classical
"paintbrush"
'a little tail, a painter's brush', diminutive of penis 'tail'; also the source of 'pencil'
2
Stage 2 of 3
Penicillium
New Latin · 1809
"brush mould"
the botanist Johann Link named this mould genus in 1809 for its brush-like spore stalks
3
Stage 3 of 3
penicillin
English · 1929
"antibiotic"
Alexander Fleming noticed in 1928 that a stray mould killed bacteria on a culture plate at St Mary's Hospital, London, and named its active substance in 1929; Howard Florey and Ernst Chain's Oxford team made it a usable drug from 1940
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Read the full story

Penicillin’s story begins in Latin: penicillus meant “paintbrush.” 'a little tail, a painter's brush', diminutive of penis 'tail'; also the source of 'pencil'. By 1809, the word had taken hold in New Latin as Penicillium. The botanist Johann Link named this mould genus in 1809 for its brush-like spore stalks. It reached English by 1929 as penicillin. Alexander Fleming noticed in 1928 that a stray mould killed bacteria on a culture plate at St Mary's Hospital, London, and named its active substance in 1929; Howard Florey and Ernst Chain's Oxford team made it a usable drug from 1940. Today, penicillin means an antibiotic produced from Penicillium moulds.