一回忌[ikkaiki] first death anniversary
一周忌[isshuuki] first anniversary of death
回忌[kaiki] death anniversary
忌まわしい[imawashii] unpleasant
忌む[imu] to avoid

忌中[kichuu] mourning
忌日[kinichi] anniversary of a person's death (on which Buddhist commemorative rites, etc. are performed)
忌避[kihi] evasion
忌憚[kitan] reserve

斎む[imu] to avoid
斎く[itsuku] to worship
斎み垣[imigaki] shrine fence
斎日[imibi] unlucky day (according to astrology)

斎戒[saikai] purification
斎戒もく浴[saikaimokuyoku] purification
斎垣[igaki] fence around a shrine
斎宮[saiguu] the ancient imperial princesses serving at the Ise shrine

諱む[imu] to avoid
忌諱[kiki] displeasure
後の諱[nochinoimina] posthumous name

偏諱[henki] one kanji in the name of a nobleperson (with a multiple-kanji name)
偏諱を賜う[henkiwotamau] (of a nobleperson) to bestow one of the kanji in one's name upon someone (e.g. a meritorious retainer, a boy coming of age, etc.)
遠諱[onki] semicentennial memorial service