One of the less elegant words in the transportation lexicon is intermodal, a term that describes the movement of a person or thing from Point A to Point B by more than one means of transportation.

The word is important, however, because there is substantial evidence that more and more transportation dollars will be spent in coming years devising ways to make intermodal operations more efficient.

Barge operators are talking to railroads, railroads are talking to truckers and truckers are talking to airlines. One of the reasons they have to talk to their competitors instead of simply buying each other out is because federal law, with some exceptions, prohibits one kind of transportation company from owning another. The elimination of many such prohibitions has been one goal of the Carter administration's deregulation drive.

A recent study from Booz, Allen and Hamilton Inc. concluded that the piggyback business -- where that big truck trailer rides between cities on a railroad flatcar -- has the potential to grow at an annual rate of 11 to 12 percent until 1990.

The study was commissioned by Transamerica Interway, which leases and maintains 40,000 piggyback trailers.

"For the development of a truly intergrated system," the study said, "the regulatory system should not only permit but encourage common ownership of the various types of carriers . . . Eliminating some of the important regulatory barriers to integrated freight transportation would permit freight dock-to-dock entity, something which is not common outside the trucking industry today."

Truck trailers on railroad flatcars now represent 7 percent of all railroad revenues and trailed only coal in terms of rail carloads in 1979.

That share should increase, the study said, because of the fuel consumption advantages of piggyback. According to the study, piggyback operations are from two to three times as fuel-efficient as straight-through trucking.

A fuel-comsumption advantage is also available in some railroad-barge connections. In early 1978, the Interstate Commerce Commission approved a single freight rate involving both a barge line and a railraod for transporting Iowa grain to New Orleans. The result was a savings of 2 or 3 cents per bushel to the shipper, according to the National Transportation Policy Study Commission.

"We think we're going to see a lot more of that," said William A. Creelman, past president of the American Waterway Operators Inc.