安危[anki] fate
危うい[ayaui] dangerous
危うく[ayauku] barely
危ない[abunai] dangerous
危ながる[abunagaru] to be afraid of

危なっかしい[abunakkashii] dangerous
危ぶむ[ayabumu] to fear
危める[ayameru] to wound
危絵[abunae] suggestive or indecent picture
危害[kigai] injury

アナログデジタル変換器[anarogudejitaruhenkanki] analog-digital converter
データ交換[deetakoukan] data exchange
パリティ変換[paritihenkan] parity transformation (physics)
メール交換[meerukoukan] exchange of letters
意見交換[ikenkoukan] exchange of ideas

引換て[hikikaete] on the contrary
下位互換性[kaigokansei] downward compatibility
かな漢字変換[kanakanjihenkan] kana-kanji conversion (on a computer, etc.)
可換群[kakangun] Abelian group
賀詞交換[gashikoukan] New Year greetings (parties)