Labor - Trench's New Testament Synonyms
Labormochthos (G3449) Labor
ponos (G4192) Toil
kopos (G2873) Weariness
Mochthos is used only three times in the New Testament and in each instance is closely related to kopos (2 Cor. 11:27; 1 Thess. 2:9; 2 Thess. 3:8). Etymologically, mochthos is closely related to mogis (G3425), which Curtius suggests is a dative plural, mogois, that has dropped a letter and subsided into an adverb. Mochthos is an everyday word for the type of labor that in one form or another is the lot of all of the sinful children of Adam. Some have suggested that the infinitely laborious character of labor (the varying degrees of distress that are inextricably and inescapably part of it) is not emphasized in mochthos to the same degree as in the other words of this group and that this constitutes the difference between mochthos and these words. But this is hardly the case. Phrases like polymochthos Ares (much-suffering Ares) and numerous others do not bear this out.
Three of the four times ponos is used in the New Testament are in Revelation (16:10-11; 21:4). The other is in Colossians (4:13), where ponos is the best reading, though there are four other readings. Ponos refers to labor that demands the greatest exertion if one is to accomplish a task. In Homer, war is always regarded as the ponos, not only of mortal warriors but also of immortal ones, even of Ares himself. Theognis refers to it as the ponos andron (toil of men). Ponos is used with deris and polemos. Ponoi is the usual word for the labors of Hercules. Less frequently they also are referred to as mochthoi. Plato used ponos with agon eschatos, nosos, kindynos, and zemia. In the Septuagint, ponos is used with odyne, mastix, and plege.The cruel bondage of the children of Israel in Egypt is their ponos (Exod. 2:11). Because of this meaning it is not surprising that ponos is expressly named as having no place in the heavenly city (Rev. 21:4).
Kopos, which occurs some twenty times in the New Testament, is the most frequently used of these three terms. Kopos does not refer so much to a person's actual exertion as to the lassitude or weariness that results from extreme straining. Kopos and the verb kopio (G2872) frequently are used to designate what are (or what ought to be) the labors of the Christian ministry. When used in this way, kopos contains a word of warning for all who are so engaged.
In conclusion, "labor," "toil" (or perhaps "travail"), and "weariness," respectively, are the three best English translations of mochthos, ponos, and kopos.