.

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Note added at 13 mins (2015-03-12 20:23:07 GMT)
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a razón social es la denominación por la cual se conoce colectivamente a una empresa. Se trata de un nombre oficial y legal que aparece en la documentación que permitió constituir a la persona jurídica en cuestión.

Lee todo en: Definición de razón social - Qué es, Significado y Concepto http://definicion.de/razon-social/#ixzz3UClYEoVG

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Note added at 14 mins (2015-03-12 20:24:16 GMT)
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company of course in its broader sense

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Note added at 17 mins (2015-03-12 20:27:12 GMT)
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RAE

denominación.
(Del lat. denominatĭo, -ōnis).
1. f. Nombre, título o sobrenombre con que se distinguen las personas y las cosas.

denominación and nombre are both name

All three concepts, including "nombre", can be translated as a single word. "Razón social" does indeed mean company name, but there's no need to keep repeating "name" as Bill suggests.

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Note added at 26 mins (2015-03-12 20:36:41 GMT)
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In other words, "name" can refer to an individual or corporation.

“Razón social” and “denominación social” are commonly used as if they were interchangeable but, strictly speaking, they are not. Strictly speaking “razón social” is a “denominacion subjetiva,” i.e., a business name that (often by law) must include the name or names of the members of the entity. For that reason, “razón social” is often translated as “partnership name” because by law the name of a partnership, i.e., a “sociedad personalista” (in Spain and elsewhere) must include at least one of the partners’ names. As an example, the general partners (“socios colectivos”) in a general or limited partnership (“sociedad colectiva o comanditaria”) are Sres. Pérez, Martínez and García. The partnership name must include all of the partners’ names (“Pérez, Martínez y García, S.C. (or) S. Com.”) or, if only Sr. Pérez is a “name partner”, the partnership name must include the abbreviation “y Cía” (and Partner/Partners), i.e., “Pérez y Cía, S.C. (or) S. Com.”

In contrast, a “denominación social” is a “denominación objetiva” that may reflect a business entity’s economic activities or merely be a fantasy name. These names may be chosen freely by those entities that by law are not required to identify the entities’ members’ names in their business name (in Spain, principally “sociedades de responsabilidad limitada” and “sociedades anónimas”, among others).

Although I have given examples from Spain, here is an explanation from the perspective of Mexican business law:

http://todoconta.com/diferencia-entre-razon-social-y-denomin...

But, again, having said all of this, “razón social” and “denominación social” are used interchangeably so often, even by lawyers, that this distinction is often lost. I once heard (an older) Spanish professor of “Derecho mercantil” explain the differences I have outlined above, but he added that most (young) “licenciados” in Derecho don’t distinguish the two.

Designation: an official name, description, or title.
So, one option could be "name, designation or trade name of the buyer"... or similar. See glossaries etc.

Spanish term (edited): nombre, denominación o razón social

It's a good idea to prefix with nombre for the full string and include accents for any future search.

Social: could be a body corporate or partnership that, in the UK and US and unless an LLP, is not a body corporate.

otra posibilidad ...

(legal) name, appellation or trade name ...

Appellation: noun
1. A name, title, or designation.
2. A protected name under which a wine may be sold, indicating that the grapes used are of a specific kind from a specific district.
3. The act of naming.

Appellation: noun
alias, appellative, assumed name, call, calling, characterization, cognomen, definition, description, designation, eponym, identification, label, moniker, name, namesake, nickname, nomenclature, nomination, patronym, pen name, pseudonym, sobriquet, style, surname, term, title
Burton's Legal Thesaurus, 4E. Copyright © 2007 by William C. Burton

trade name / business name:
Names or designations used by companies to identify themselves and distinguish their businesses from others in the same field.
West's Encyclopedia of American Law, edition 2. Copyright 2008 The Gale Group, Inc. All rights reserved.


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Note added at 6 hrs (2015-03-13 02:57:06 GMT)
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example:
The Korea Trademark Law article 51.1 allows free use of the trademarks inadequate to permit exclusive use to a specific person and necessary to guarantee public use. The clause 1 of this article provides the usual way to use their own name, appellation or business name etc. and the clause 2 provides the usual way to use the generic names or descriptive signs of the goods.

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Note added at 7 hrs (2015-03-13 03:10:18 GMT)
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y otra posibilidad es:
denomination or business name

ejemplos en:
1. http://enforcement.trade.gov/tomato/2013-agreement/Mex-Tomat...
2. http://archive-mx.com/page/717176/2012-11-21/http://www.nota...
3. http://unpcdc.org/media/8050/paraguy 1.pdf
4. http://www.wipo.int/edocs/lexdocs/laws/en/pe/pe042en.pdf



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Note added at 1 day7 hrs (2015-03-14 03:30:26 GMT)
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...about the use of the word appellation, you can "google" the sentence "Mark Twain is the famous appellation by which everyone remembers author and humorist Samuel Clemens. for example or "The unique weather and climate of Antarctica provide the basis for its familiar appellations—Home of the Blizzard and White Desert." or "The custom of the Easter lamb appropriates both the appellation used for Jesus in Scripture (“behold the lamb of God which takes away the sins of the world,” John 1:29) and the lamb’s role as a sacrificial animal in ancient Israel." between many others from the "Encyclopedia Britannica"