adelphos

Adelphos (Greek: ἀδελφός) is a noun meaning "brother." The standard masculine plural is adelphoi (Ἀδελφοί). The feminine form is adelphē (ἀδελφή) with the plural adelphaí (ἀδελφαί), meaning "sisters." The term is one of the core words for kinship in Greek and has given rise to various compound forms in scholarly and religious vocabulary.

In classical Greek, adelphos primarily referred to a male sibling but could also denote a fellow member of a group, such as a fellow citizen, comrade, or member of a kinship or religious circle. The word often conveyed a sense of close affiliation or solidarity beyond mere blood relation, depending on context.

In early Christianity, adelphos is widely used to denote fellow believers as "brothers" or "brethren," emphasizing spiritual kinship within the community. This usage recurs throughout the New Testament and later Christian writings, where the term signals mutual obligation and fraternity among members of the faith.

Modern usage in Greek retains the basic sense. In Modern Greek, the everyday word for "brother" is αδελφός (adelphós), with sister as αδελφή (adelphí); plural forms are αδελφοί (adelphoí) for brothers and αδελφές (adelphés) for sisters. In English-language scholarship, adelphos is encountered mainly in historical, philological, or theological discussions; it is not a common modern term outside those contexts.

Overall, adelphos functions as a fundamental word for familial and communal kinship in Greek, with enduring significance in both secular and religious writings.