Discussion: "reentrant" as a real word

Before I started orienteering, I had never heard or seen in print the word "reentrant". Likewise after I stopped. I always thought it was one of those made up or fake jargon words that no one would ever use outside the context or orienteering, as did everyone else. Like "hey dude, lets hike up the reentrant". Really?

Who knew that the word appears in major British literature. Quoting from the first paragraph of chapter 13 of Watership Down by Richard Adams

The corner of the opposite wood turned out to be an acute point. Beyond it, the ditch and trees curved back again in a reentrant, so that the field formed a bay with a bank running all the way round

(even my spell checker doesn't like it)

Anyway, had to share. For those who don't know, Watership Down is a book about rabbits, (who I suppose would be more in tune to reentrant like things) that is really about people which they make most Stateside grade schoolers read, but I'm rereading cuz its pretty good.

So, if you ever see the word "reentrant" outside the context of orienteering, please post.

I don't recall the exact passage, but it appears in C.S. Lewis' Out of the Silent Planet when the protagonist (Ransom?) is observing the Martian terrain.

I liked Watership Down, but didn't remember the use of reentrant. Thanks for the reference. I've very occasionally heard of reentrant as being a geographic term, but seemingly much less used than "draw" or such. For land navigation training for my search and rescue unit, I used the term "valley" instead of reentrant, thinking that no-one would recognize the latter, but then was criticized for using the former incorrectly. Maybe I should have just kept reentrant!

For you folks down under, they're talking about gullies.

Thanks, I never would have known. I think they use it in NZ though and they're just as under as we are.

Also used in programming.

Thanks jjcote. Just looking at the word - it makes no sense to be an equivalent of gully - well in my mind.

I think there are a lot of made up words in computing.

I've known the computing version for a long time, but didn't ever come across the other meaning outside of orienteering.
The German equivalent is much more common, but often (or should I say, usually?) confused with a depression.

It's a similar situation in Spain. Vaguada is the word in Spanish, but most Spaniards can't define what it is. The word itself, however, is familiar to many people, particularly in the Madrid area. But that's only because there's a shopping center named La Vaguada.

Kipling uses it. Can't remember quite where, maybe in "The man who would be king" because I haven't read much Kipling. Probably you can get fired for doing so in universities nowadays.

I was trying to describe a reentrant to a friend from southern Indiana, and he finally said, "Oh, you mean a holler!"

Noun. In an irregular polygon, an interior angle that is greater than 180°, reentrant angle.

In a military star-shaped fortress, the inward angle between two saliants. (Saliant = a piece of land or section of fortification that juts out to form an angle.)

Well I never knew you could interrupt your run when you come to a re-entrant. That will make orienteering much more pleasant.

I _think_ I heard about (and had controls located in) reentrants on orienteering trips to the UK a few years before I read about it in a programming context. It still makes more sense in the latter usage IMHO. I.e. a piece of code which carries no external state, so that it can be started an arbitrary number of times before the previous run(s) have finished.

How about in my real life scenario: I entered the Aus MTB Orienteering champs but had to withdraw due to injury. I healed faster than expected, signed up once more thus becoming a reentrant.

No, that's the definition of reentry.

Seems I can make up my own definition and if used enough it'll get accepted in common vernacular.

From my colleagues in Edinburgh. Observation of a reentrant phase transition in incommensurate potassium

If tRicky wins/won those MTB champs, everyone can rave about how a reentrant won the race -- and get it into the dictionary as a noun!
I always assumed 'reentrant' was a British thing referring to water re-entering the system. Great to have a generic word to cover holler, hollow, valley, gully, ditch, and those shallow 'dips' in the hill side.

If I won those races in my current condition it'd be a miracle.

My opinion of US grade school education ticks upwards slightly - Watership Down is totally absent from Canadian curricula as far as I know.

For a quantum leap, make them read Out of the Silent Planet. And heck, why not, Perelandra and That Hideous Strength too?

No, I'm not serious. Haven't got around to That Hideous Strength myself as yet.

I just found this paper by accident. Haven't had the time to look at it!

Brown SR Ph.D.. Reentrant emergence. American Philosophical Quarterly 2009; 46(3): 225-238.

My wife cites AVRT, a supraventricular tachycardia.

A very nice explanatory video.