Suppose that you hold an option that must be exercised "within 30 days prior to the expiration of the option".  Does this mean that you must exercise the option no later than thirty days before the expiration date or that you may exercise the option at any time within the 30 days before the expiration date?

In Wilson v. Gentile, 8 Cal. App. 4th 759 (1992), the Court of Appeal found that the latter construction was both "natural and logical".  However, this interpretation creates a problem for the optionor - it may not know until the last minute whether an option will be exercised.  According to the Court:

Faced with this absurd result, the courts early on decided to rescue lessors from their poor choice of words and treat the word "within" as if it did not exist.  Some courts indeed use the technical grammatical term and describe the word "within" when inserted in such an option provision as a "pleonasm" [a redundancy].  However, as we have seen from other contexts, the word "within" is not always a pleonasm merely because it appears in juxtaposition with the term "prior to."  So it is not a pleonasm as a matter of grammatical construction but a pleonasm only when a court chooses to treat it as such in order to avoid what the court perceives to be an absurdity as a matter of presumed intent of the parties or of public policy.

The Court ultimately decided that in the context of an option to buy, "within 30 days prior to" the expiration of the option period is properly interpreted to allow exercise of the option during the 30-day period immediately preceding the expiration of the option.

Speaking of pleonasms, I'm still looking for an opportunity to cite California Civil Code Section 3537 ("Superfluity does not vitiate").