Can I suggest dropping 'reduced' or 'bore' or 'reduced bore' into the search box and you will get more than enough info. If not, then feel free to drop a line.
Usually we expect an engineer to be techno-savy enough to be able to do a Google search. Searching "reduced full bore valve" in Google gets you your answer on the first hit.
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"The problem isn't working out the equation,
its finding the answer to the real question." BigInch
Words and sacrosanct definitions are such fine things, but Google mght not directly tell you e.g. that a butterfly valve is a fashion sort of a reduced bore valve (one would however find that out if one tried to crawl through the line, or try to pass any large device or a solid pig through it!) ;>)
other than full bore ball valves and some gate valves, most valves either have a reduced cross sectional area through the valve or have a cross section that may not be circular or aligned with the pipe. The may be considered to have a reduced port size. Full bore ball or gate valves would be necessary for a pigging operation and for reduction of minor losses.