Reader question:

In this sentence – "Mom, you should put some of your things away. Baby proof this house," stated our oldest son Mark as he lumbered² up the stairs followed by his wife, Kim, and fifteen-month-old Hannah – what does "baby proof this house" mean? And the phrase "lumbered up"?

My comments:

The easier part first. When someone lumbers³, he walks heavily, as though his legs were clumsy trunks of wood. Lumber¹ is the log of a tree.

As for "baby proof the house", that's proof working as a suffix⁴. Baby-proof, actually (best with a hyphen if it's a newly coined combination but a lot of people do simply write these things as one word – babyproof – or two words – baby proof).

To baby-proof the house means to make sure the baby won't mess up the room. Mark's suggestion being: Mom, you should put some of your things away so that the baby won't have anything to play with (and hence mess up with). Babies being babies, they mess things up. That's not a fault. That's just them being themselves and having fun.

Anyways, proof as a suffix means something is resistant⁵ to or able to withstand harm. I'll give you many examples for you to have a fuller idea.

You've heard of waterproof⁶ watches, haven't you? A waterproof wristwatch, for example, is fully⁷ protected from water and allows you to go swimming with one.

Similarly, in a weatherproof coat, you may walk in the rain. In fact, I came to work in a weatherproof overcoat today, while braving the early morning drizzle⁸.

There are all sorts of things that are, er, something-proof. A rabbit-proof fence, for instance, is one that doesn't have holes big enough for rabbit to squeeze in through. A bulletproof window is, yes, able to withstand bullets. And there are metal doors that are touted⁹ as burglar-proof. Well, in that case, don't take it literally¹⁰ – if you lose something to burglary, I am afraid your burglary-proof front door will prove nothing more that there are burglars roaming your area.

And there are foolproof manuals, instructions that are so simple that you'll be able to master it even if you were, er, a fool. Here, foolproof means infallibly effective, absolutely easy to follow. Likewise, a "foolproof identification system" will be able to read who people are without fail. A foolproof safety lock, on the other hand, is absolutely secure.

Here are a few real examples culled¹¹ from the media.

1. explosion-proof (won't explode):

"Explosion-proof" products are capable of containing an explosion. The term "explosion-proof" does not indicate that the product is capable of withstanding an external explosion, but only of withstanding an internal explosion without allowing flames or hot gases to escape from the transducer housing to trigger an explosion in the surrounding atmosphere.

- www.setra.com

2. stormproof (able to withstand storms):

Task: Stormproof power lines. Cost: Big zap to utilities' coffers

After being slammed by eight hurricanes in the past two years, Florida residents are angry about sitting in the dark.

It has prompted legislators and regulators to ask tough questions about how the state's power system can be "hurricane proofed."

- Electricity Forum¹² News, January 6, 2007

3. foolproof (safe, impervious¹³ to human interference, error, or misuse):

Pakistan's nuclear program has "foolproof" and "second to none" security, the head of the program insisted today, calling doubts about the safety of Pakistan's nuclear arsenal¹⁴ "inaccurate¹⁵" and "based on a lack of understanding."

- Pakistan Calls Nuke Program Security 'Foolproof', ABC News, January 26, 2008.

4. burglarproof (free from burglary):

How to Burglarproof Your Home

Step 1:

Keep windows closed and doors locked – don't take chances for even a few minutes. Use a 1-inch dead bolt for each exterior¹⁶ door. Secure sliding glass doors by inserting a broomstick or dowel in the inside track.

Step 2:

Consider installing an alarm system or motion-detecting lights.

...

Step 7:

Keep jewelry¹⁷ and other valuables in a safe.

Step 8:

Consider getting a dog – many kinds of dogs will make enough noise to discourage burglars (see 'eHow to Select a Dog Breed').

Step 9:

Leave spare keys with a neighbor rather than hidden outside your house.

Step 10:

Keep shrubs¹⁸ and bushes trimmed so that they can't conceal¹⁹ prowlers.