<Li> SECS stands for "SEMI equipment communication standard", in which SEMI stands for "Semiconductor equipment manufacturing industries". </Li> <Li> AIM stands for "AOL Instant Messenger", in which AOL stands for "America Online". </Li> <Li> HASP stood for Houston Automatic Spooling Priority, but spooling itself was an acronym--simultaneous peripheral operations on - line </Li> <P> Some macronyms can be multiply nested: the second - order acronym points to another one further down a hierarchy . In an informal competition run by the magazine New Scientist, a fully documented specimen was discovered that may be the most deeply nested of all: RARS is the "Regional ATOVS Retransmission Service"; ATOVS is "Advanced TOVS"; TOVS is "TIROS operational vertical sounder"; and TIROS is "Television infrared observational satellite". Fully expanded, "RARS" might thus become "Regional Advanced Television Infrared Observational Satellite Operational Vertical Sounder Retransmission Service". However, to say that "RARS" stands directly for that string of words, or can be interchanged with it in syntax (in the same way that "CHF" can be usefully interchanged with "congestive heart failure"), is a prescriptive misapprehension rather than a linguistically accurate description; the true nature of such a term is closer to anacronymic than to being interchangeable like simpler acronyms are . The latter are fully reducible in an attempt to "spell everything out and avoid all abbreviations," but the former are irreducible in that respect; they can be annotated with parenthetical explanations, but they cannot be eliminated from speech or writing in any useful or practical way . Just as the words laser and radar function as words in syntax and cognition without a need to focus on their acronymic origins, terms such as "RARS" and "CHA2DS2--VASc score" are irreducible in natural language; if they are purged, the form of language that is left may conform to some imposed rule, but it cannot be described as remaining natural . Similarly, protein and gene nomenclature, which uses symbols extensively, includes such terms as the name of the NACHT protein domain, which reflects the symbols of some proteins that contain the domain--NAIP (NLR family apoptosis inhibitor protein), C2TA (major histocompatibility complex class II transcription activator), HET - E (incompatibility locus protein from Podospora anserine), and TP1 (telomerase - associated protein)--but is not syntactically reducible to them . The name is thus itself more symbol than acronym, and its expansion cannot replace it while preserving its function in natural syntax as a name within a clause clearly parsable by human readers or listeners . </P>

Words made out of letters of other words