Abandonment of a commitment, pact or relationship with which someone, person or group, was linked by explicit or implicit agreement. It involves disloyalty, infidelity and clumsiness and presupposes disappointment for the one who had put the trust in the one who commits such an action.
It is evident that the morality of this action depends on the duty that permanence in membership implied. And that if it is a bad cause, the sooner the abandonment occurs, the less charged is the conscience of an undue moral responsibility.
Pedro Chico González, Dictionary of Catechesis and Religious Pedagogy, Editorial Bruño, Lima, Peru 2006
Source: Dictionary of Catechesis and Religious Pedagogy
jettema (htthma, 2275), primarily decrease, diminution; denotes loss. It is used of the loss suffered by the Jewish nation in the fact of having rejected the testimonies of God and his Son, and the gospel (Rom 11:12), the reference being not only to the national loss, but also to the spiritual loss. From this, the word that is used as a contrast is pleroma, plenitude. In 1Co 6:7 the reference is to the loss suffered by the church in Corinth due to their discord and their contentious ways of acting, in appealing to the judges of the world. Here the RVR translates “fault”, like the RV and the RVR77 (VM: “serious fault”). The previous adverb, “already”, originally shows the global nature of the defect; the loss affected the whole church, and was “a total detriment.” In the LXX, in Isa 31:8 the word means the loss of a defeat, referring to the calamity suffered by the Assyrians; lit., “her young men shall be for loss” (ie: “taxpayers”). See MISSING.¶ Cf. jettao, to make inferior, used in the passive voice, to be overcome (from spiritual defeat, 2Pe 2:20), and the adjective jetton or jesson, less, worse.
Source: Vine New Testament Dictionary