I've seen it, and yes it is equivalent, although according to the following, its primary usage is "being in the direct line, as a descendant or ancestor".

http://dictionary.reference.com/browse/lineal?s=t

According to my 'Roget's Thesaurus' (YES, I still have one and what's more, I actually know how to use it), the word 'lineal' is indeed a synonym for 'linear', when used as an adjective and the meaning is either 'straghtness' or 'continuity'.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

According to MY dictionary (Macquarie Australian), the primary meaning of "lineal" is "being in the direct line (e.g. as a direct descendant)".

The third meaning given is as a synonym for "linear".

I would definitely use "linear metre / foot" rather than "lineal meter / foot" for the OP's example of load or weight per unit length.

http://julianh72.blogspot.com

robyeng,

"Lineal" is in the Oxford dictionary my mom used to play Scrabble. That makes it correct. :)

I was told by one of my teachers in college not to put the "s" after "lb". "lb" is Latin.

Why can't you call it lb/ft. Is there some other use of linear units that require you to note that they are linear?

--
JHG

I see this all the time... when buying carpet! Always throws me for a minute. Why can I buy timber by the linear metre, but my carpet comes in lineal metres? I've even subconsciously made the association: lineal - linoleum. Interestingly, the word root is the same (linum - flax) though the derivation diverges (flax -> rope -> line, compared to flax -> linen -> canvas).

I put my example down to la-di-da fashion marketers elevating their decorative wares over the mundane timber and metal industry with an inflective "al" on the end of "linear". But that doesn't explain its use in your USA book!

I guess linear/lineal is used to differentiate between diameter, just to remove the potential confusion..

Reminds me of the joke "This is sure a wide runway!" "But look how wide it is"

I see this one messed up a lot. For some reason people have a hard time thinking in terms of weight per linear foot (which is actually a very odd surrogate for density, but very useful). I can't tell you how many times I've seen engineers assume that lbm/ft or kg/m was actually lbm/ft^3 or kg/m^3 and get some very odd load-out weights. Adding the qualifier "linear" or "lineal" helps prevent that particular nonsense.

As to "linear" vs. "lineal" people really do want their work to seem important. Somehow many think that using terminology that is not in broad usage makes it look more important. It doesn't, but people want it to. When I see "lineal" I think "linear" and go on about my life leaving them to their little triumph. If I have to reply in writing to someone who insists on "lineal", I respond with "linear" because I cannot bring myself to participate in their pomposity. If they have the temerity to correct me on that point I just ignore them.

David Simpson, PE
MuleShoe Engineering

Law is the common force organized to act as an obstacle of injustice Frédéric Bastiat

The industries that use the term lineal also commonly use the term areal. Area is a noun and areal is an adjective. In composites "areal fiber weight" (AFW) is a very commonly used term. Where areal is used lineal is simply logically consistent.

FWIW, the Dictionary of the Real Academia Española recognizes the words linear and lineal but doesn't admit linearidad, just linealidad.

[off topic]
Spanish is a strange one - when I was working on underwater cable systems, we had to identify lasers as male (el ...) and receivers as female (la ...). Never thought about it until I accidentally type la for a laser and was told "you can't do that - lasers are male! It has to be el". Guess it is the same in all the Latin based languages.
[/off topic]

One thing to keep in mind for pipelines, etc, that have a large vertical component in their profile: the centerline length and the horizontal length (i.e. the plan view length that is stationed) can be quite different. I once had a contractor request payment for the centerline length of a pipeline, which was about 25 feet more than the horizontal length stated in the contract. He was not amused when I showed him in the Special Provisions that the definition of "linear foot" as it applied to the pipeline was for the horizontal length, not the centerline length. He was hoping to talk his way into another $3,500 or so. For this reason, I now typically use "horizontal foot" and "HF" in the bid form and definitions instead of "linear foot" and "LF", because this states even more clearly my intent.

==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

xwb,

The Awful German Language, by Mark Twain. Read the Tale of the Fishwife and its Sad Fate.

--
JHG

off topic,

I once worked with a man from Argintina who said he went to buy a piece of lumber. He asked for "a two by four 8 feet long." Get this guy a 2x4 8 foot long. Next time he asked for "a 2x4 8 foot long." Oh -- you want an 8 footer. Now he was really confused and did not know for next time if he should feet foot or footer.

Design for RELIABILITY, manufacturability, and maintainability

off topic

I put my shirt in the wash and it shrinked
Err no, it shrank ...
Hmmm.. it shrunk ...
I've gone fatter since it was washed