IPA: /ˈmɑːrtərdəm/
KK: /ˈmɑrtərˌdʌm/
The condition of suffering or dying for a cause, especially for one's beliefs or faith.
Many people throughout history have faced martyrdom for their beliefs.
Martyrdom is formed from "martyr" (from Greek "martus", meaning witness) and "-dom" (meaning state or condition). The term refers to the state of being a martyr, or one who witnesses to their faith, often at the cost of their life.
Think of a 'witness' ('martyr') who is in a special 'state' ('-dom') because they have sacrificed themselves for their beliefs.
No commonly confused words.