下位互換性[kaigokansei] downward compatibility
互い[tagai] mutual
互いに[tagaini] mutually
互い違い[tagaichigai] alternate
互い違いに[tagaichigaini] alternate

互に[katamini] mutually
互角[gokaku] equality
互換[gokan] transposition
互換性[gokansei] compatibility
互恵[gokei] reciprocity

御出でになる[oideninaru] to be
御珍々[ochinchin] penis
御田[oden] oden
御鍋[onabe] pot
御負けに[omakeni] to make matters worse

御呪い[omajinai] good luck charm
御襁褓気触れ[omutsukabure] diaper rash
御目出度う御座います[omedetougozaimasu] congratulations
御握り[onigiri] rice ball (often triangular, sometimes with a filling and wrapped in nori)
御陰[okage] grace (of God)

御蔭様[okagesama] (somebody's) backing
御客様[okyakusama] guest
お子様[okosama] child (someone else's)
お生憎様[oainikusama] that's too bad (ironical)
御待ち遠様[omachidoosama] I'm sorry to have kept you waiting

御疲れ様[otsukaresama] thank you
御母様[okaasama] mother
ご苦労様[gokurousama] thank you very much for your ...
御馳走様でした[gochisousamadeshita] That was a delicious meal (said after meals)
様を見ろ[zamawomiro] serves you right!