Word of the Day: Heir Apparent

This is the word bouncing around inside my head this morning.
The American Heritage Dictionary defines heir apparent as "an heir whose right to inheritance is indefeasible by law provided he or she survives an ancestor." That sentence was too confusing to me. I read it 7 times before I started to get it. Well, and I also looked up its antonym: heir presumptive, meaning "an heir whose claim can be defeated by the birth of a closer relative before the death of the ancestor." That made more sense.

The plural of heir apparent is heirs apparent, much like how the plural of passer-by is passers-by (which can also be written as one, non-hypenated word). Not totally obvious to the average American. I was saying passer-bys for many years. I also said "for all intensive purposes" instead of "intents and purposes" - and KC was the one to correct me. I thank you, KC, for saving me from future embarrassment.