Because, conj.
Etymology: [OE. bycause; by + cause.]
1. By or for the cause that; on this account that; for the reason that. Milton.
2. In order that; that. [Obs.] And the multitude rebuked them because they should hold their peace. Matt. xx. 31. Because of, by reason of, on account of. [Prep. phrase.] Because of these things cometh the wrath of God upon the children of disobedience. Eph. v. 6.
Syn, -- Because, For, Since, As, Inasmuch As. These particles are used, in certain connections, to assign the reason of a thing, or that "on account of" which it is or takes place. Because (by cause) is the strongest and most emphatic; as, I hid myself because I was afraid. For is not quite so strong; as, in Shakespeare, "I hate him, for he is a Christian." Since is less formal and more incidental than because; as, I will do it since you request me. It more commonly begins a sentence; as, Since your decision is made, I will say no more. As is still more incidental than since, and points to some existing fact by way of assigning a reason. Thus we say, as I knew him to be out of town, I did not call. Inasmuch as seems to carry with it a kind of qualification which does not belong to the rest. Thus, if we say, I am ready to accept your proposal, inasmuch as I believe it is the best you can offer, we mean, it is only with this understanding that we can accept it.
Shades of meaning
Because, literally by-cause, is the most direct and complete word for giving the reason of a thing. Since, originally denoting succession in time, signifies a succession in a chain of reasoning, a natural inference or result. As indicates something like, coordinate, parallel. Since is weaker than because; as is weaker than since; either may introduce the reason before the main statement; thus, since or as you are going, I will accompany you. Often the weaker word is the more courteous, implying less constraint; for example, as you request it, I will come, rather than I will come because you request it. Inasmuch as is a formal and qualified expression, implying by just so much, and no more; thus, inasmuch as the debtor has no property, I abandon the claim. For is a loose connective, giving often mere suggestion or indication rather than reason or cause; as, it is morning, for (not because) the birds are singing.