How do you pronounce "radioactivity"?

In American English: /ˈreɪdiːoʊˌækˌtɪvəˌtiː/ (RAYD-ee-oh-ak-tiv-uh-tee). In British English: /ɹˌeɪdɪəʊaktˈɪvɪti/ (r-ayd-i-OH-akt-iv). In Canadian English: /ˈreɪdiːoʊˌækˌtɪvəˌtiː/ (RAYD-ee-oh-ak-tiv-uh-tee). In Australian English: /ɹˌeɪdɪəʊaktˈɪvɪti/ (r-ayd-i-OH-akt-iv).

Is "radioactivity" pronounced differently in American and British English?

Yes. In American English it's pronounced /ˈreɪdiːoʊˌækˌtɪvəˌtiː/ (RAYD-ee-oh-ak-tiv-uh-tee), while in British English it's /ɹˌeɪdɪəʊaktˈɪvɪti/ (r-ayd-i-OH-akt-iv).

How to Pronounce "radioactivity"

radioactivity

regional

/ˈreɪdiːoʊˌækˌtɪvəˌtiː/

RAYD-ee-oh-ak-tiv-uh-tee

Syllable Breakdown

reɪdra·iːdi·oʊo·ækac·tɪvtiv·əi·tiːty

Source

80%confidence📘 CMU Pronouncing Dictionary v0.7b

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Last updated: 2026-02-14