Of and relating to Dispensation
Basically - (oikonomia) refers to the act of administering. The word was used of management or administration of a household. When used in the NT it is either the ACT of administrating or the TIME the act of administration is carried out. It is translated "stewardship" in Luke 16:2,3,4 and relates to the job of a steward. A steward administers or disperses duties of the household i.e. he is accountable for all things consisted in running a household; delegating jobs to servants, finances, generally making sure that things ran smoothly. Not every steward would have the same responsibility; it would depend on how his "boss" would want him to administer or dispense responsibility within the household. This can also be said of a person regarding the running of governmental affairs.
oikonomia is also translated administration/dispensation. In the following scripture administration and dispensation can be interchangeable both having the same meaning: 1 Corinthians 9:17, Eph. 1:16, Eph. 3:2, Col. 1:25
Definitions from Webster's Dictionary 1828:
steward - a man employed in great families to manage the household
administration - 1) The act of administering; direction; management; the conducting of any office or employment 2) The executive part of government, consisting in the exercise of the constitutional and legal powers, the general superintendance of national affairs and the enforcement of laws 3) The persons collectively who are entrusted with the execution of laws, the chief magistrate and his council; or the council alone 4) dispensation; distribution, exhibition of the sacrament or of grace 5) the management of the estate (of an intestate person), under a commission from proper authority, this management consists in collecting debts, paying debts (and legacies and distributing the property among the heirs)
dispensation - 1) distribution; the act of dealing out to different persons or places 2) the dealing of God to his creatures; the distribution of good and evil, natural or moral in the divine government 3) the granting of a license or the license itself to do what is forbidden by laws or canons or to omit something which is commanded; that is the dispensing with a law or canon or the exemption of a particular person from the obligation to comply with its injunctions 4) that which is dispensed or bestowed; a system of principles and rites enjoined; as the Mosaic dispensation, the gospel dispensation including the former Levitical law and rites, the latter the scheme of redemption by Christ.
That is the totality of what the word "oikonomia" means.
So speaking only for myself and my understanding - There are three distinct classes of people in the word of God - Jews, Gentiles and the church of God (1 Cor. 10:32) God dealt with each class of people differently and at different times (dispensations/administrations) through different means. What He may have said to one group is written for my learning, i.e. I can learn from what was said but it may not be applicable to me specifically.
I hope this makes sense!