Divorce court is now open for these troublesome couples.

Reluctantly joined by similar spellings or pronunciation, the following pairs of words (and two menages a trois) still seem to be giving newsletter editors trouble, as evidenced in publications recently reviewed. Let's aim for a permanent separation.

Note that when the distinctions are subtle, the usage books invariably state, "But careful writers will...." Are you a careful writer?

* Assure, insure, ensure--"To assure means to make (someone else) confident about something when the element of doubt is present. Both to ensure and to insure also mean to make certain of something. Despite the journalistic trend away from the traditional use of insure, most careful writers still prefer ensure except to denote the reduction of risk" (New York Public Library Writer's Guide to Style and and Usage).

"Ensure, insure, and assure are interchangeable in many contexts where they indicate the making certain or inevitable of an outcome, but insure sometimes stresses the taking of necessary measures beforehand, and assure distinctively implies the removal of doubt and suspense from a person's mind" (Webster's Ninth New Collegiate Dictionary, as quoted in Webster's Dictionary of English Usage).

* Careen, career--"To careen is to lean over or sway, like a boat in the current. To career is to move erratically at high speed. Careen seems to be replacing career as an all-purpose verb for both these meanings and is most frequently used by journalists; however, many careful writers preserve the distinction between the careening of a boat between buoys and the careering of race cars around a slippery track" (NYPL).

"Occasionally confused when describing runaway vehicles and the like. Careen should convey the idea of swaying or tilting dangerously. If all you mean is uncontrolled movement, use career" (Bryson's Dictionary of Troublesome Words).

* Flounder, founder--"Founder means to sink, either literally (as with a ship) or figuratively (as with a project). Flounder means to flail helplessly. It too can be used literally (as with someone struggling in deep water) or figuratively (as with a nervous person making an impromptu speech)" (Bryson).

"A person who flounders is struggling or flailing clumsily. A ship that founders fills with water and sinks; this word can also mean collapse or fail" (NYPL).

* Nauseous, nauseated--This is one of my favorites, if only because when a person says, as many commonly do, "I feel nauseous," they're stating that they cause nausea.

"'Martinez left early, complaining that he feld nauseous' (Newsweek). Make it nauseated. Nauseous is an adjective describing something that causes nausea ('a nauseous substance'). As Bernstein neatly put it, people who are nauseated are no more nauseous than people who are poisoned are poisonous" (Bryson).

"Nauseous once meant 'causing nausea" but has come to mean 'affected by nausea.' ... However, many careful writers still fervantly observe the distinction; it functions much like a secret handshake between alumni of a certain school of grammar (NYPL).

* Peak, peek, pique--"These homophones have a way of being muddled by nodding writers" (Webster's). But their different meanings are certainly clear. Peak means the pointed top of a mountain or ridge. Peek means to look or glance quickly or furtively. Pique means to excite (interest, curiosity, etc.) and to affect with sharp irritation and resentment (as in wounded pride).

* Parameter, perimeter--I dislike both of these overused words so much I once wrote a headline, "Parameter, perimeter--let's call the whole thing off."

"Perhaps because both words denote a limiting or constraining factor, parameter, a mathematical term meaning an arbitrarily defined constant, has crept into general usage to mean a boundary that helps define something, that is, a characteristic element. Perimeter is the boundary of a body or a figure, or a line around the outer limits of an area. Parameter is misused in the sense of being within a proper range ('Getting coffee is not within the parameters of Beth's job') or in the sense of a requirement ('The parameters for entrance to the class were extensive') (NYPL).

In other words, unless you're a mathematician, it's safe to avoid parameter altogether.

* Pour, pore--Pore means to read or study attentively, but it is quite common to see pour in its place. "This mistaken use of pour is a recent development for which we have little evidence. It seems to be more common in less attentively edited publications, but its chances of ever becoming standard seem somewhat dim--if only because a phrase like 'couples and families pouring over the racks of home viewing choices' calls to mind such strange images, as of cascading couples and fluid families" (Webster's).

"Occasionally pour appears where pore is intended. As a verb, pore means to examine carefully ('She pored over the documents') or, more rarely, meditate. Pour indicates a flow, either literally ('He poured the water down the drain') or figuratively ('The rioters poured through the streets')" (Bryson).

* Precede, proceed--"These words are confusing for reasons of similar pronunciation and spelling. To precede means to go before or in front of; to proceed means to go forward or move ahead. Bernstein says that the commonest error is spelling preceding 'preceeding'" (NYPL).

* Principle, principal--Here's that old troublesome couple we all first met in grade school, where they taught us that the school principal was our "pal." I always maintained the distinction with the mantra that "my principal has no principles"--a phrase gaining new currency with the recent unprincipled actions of some corporate principals.

"Principle means fundamental and is usually applied to fundamental beliefs or truths ('It's not the money, it's the principle') or to fundamental understandings ('They have signed an agreement in principle'). It is always a noun. Principal can be a noun meaning chief or of first importance ('He is the school principal') or an adjective with the same meaning ('The principal reason for my going ...') (Bryson).