Standard Lemma guide

nafcillin

noun · 2 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

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  • General-American: /næfˈsɪl.ɪn/
  • rhymes with -ɪlɪn

1

noun

Meaning 1

A semisynthetic penicillin that is resistant to beta-lactamase and is used especially in the form of its hydrated sodium salt C21H21N2NaO5S·H2O as an antibiotic.

Definition source: English Wiktionary via Wiktextract

Usage: uncountable

Topics: medicine, pharmacology, sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

2

noun

Meaning 2

a penicillinase-resistant form of penicillin (trade name Nafcil) used (usually in the form of its sodium salt) to treat infections caused by penicillin-resistant strains of staphylococci

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: Nafcil

Antonyms: none provided

Broader terms: penicillinase-resistant antibiotic

History

Etymology

From naph(thalene) + -cillin (“6-aminopenicillanic acid derivative”).