If this is the term I'm thinking of it's a really good question.
Didn't allegretto mean a little faster than allegro at one time, and then a little slower than allegro at another time? I think this is the one.
In that case, it depends when the piece was written and who wrote it.
aewanko, you've got to include your source. Man....
Oxford Music online says...
Allegretto
(It., diminutive of allegro).
A tempo (and mood) designation, normally indicating something a little less fast, and perhaps a little more lighthearted, than Allegro. But there is some evidence that in Paris around 1800 it was understood to be faster than allegro, most specifically in J.B. Cartier's L'art du violon (Paris, 1798) and in Renaudin's Plexichronomètre readings (see B. Brook La symphonie française, Paris, 1962, i, 318). It is found occasionally in Vivaldi and Domenico Scarlatti, but hardly at all in their precursors, even though Brossard mentioned the word in his Dictionaire of 1703. During the second half of the 18th century it came into special popularity, for the idea of a fastish tempo that should on no account show any sign of hurry was peculiarly appropriate to the galant style. Leopold Mozart (1756) said it should be performed ‘prettily, frivolously and jokily’ (‘artig, tändelend und scherzhaft’). When included in graduated lists of tempo marks it was normally placed between allegro and andantino. Unlike allegro, it is current only in musical contexts.
The slow movement of Beethoven's Seventh Symphony is perhaps the most famous example of allegretto, and a glimpse of the word's precise nature may result from the attempt to consider how that movement would have been affected if Beethoven had chosen instead to mark it andantino. He marked the second movement of his Quartet op.59 no.1 allegretto vivace e sempre scherzando, presumably in an attempt to suggest a fast tempo with the minimum of metrical accentuation and a maximum of fluidity.
For bibliography see Tempo and expression marks.
David Fallows
The Oxford Dictionary of Music says...
Allegretto
(It.).
Moderately quick, pretty lively (but not so much as allegro). Allegrezza. Mirth, cheerfulness.
The Oxford Companion to Music says...
allegretto
(It., dim. of allegro).
A tempo faster than andante but slower than allegro and in a lighter style. The term is also used for a short piece or movement with the tempo marked allegretto or allegro.
I like the first definition better.