single word requests - Subsequent, Consequent... Presequent?

Imagine the following:

A -> B

B is consequent (and subsequent) to A, because A implies B.

How might one describe A relative to B? "Presequent" gets a few search results... but perhaps there's a better-established word?

Another example:

Because it rained, the grass is wet.`

The wet grass is consequent to the rain. How can one make a similar statement about the rain itself?

Answer

You could say that the rain is antecedent to the grass getting wet. The Oxford English Dictionary writes that:

A thing or circumstance which goes before or precedes in time or order; often also implying causal relation with its consequent.

So, antecedent is often paired with consequent. They write further that in logic:

Hence, in various special applications, of which the logical and grammatical are the earliest uses of the word in English: Logic. (Opposed to consequent.) The statement upon which any consequence logically depends; hence †(a) The premisses of a syllogism (obs.); (b) The part of a conditional proposition on which the other depends. †(c) By some early logicians the subject and predicate were called antecedent and consequent.

For example, a usage in writing is:

1870 F. C. Bowen Logic v. 128 All Hypothetical Judgments obviously consist of two parts, the first of which is called the Condition or Antecedent.