1. The space enclosed by the extended forefinger and thumb.
2. The summarizing section of a discourse; a review or recital of a series of sermons or addresses.
3. A dash or flourish at the end of a word (similar to curlicue); any trifle or oddity; peculiarities or oddities of manner.
The first definition refers to the space between finger and thumb, not to the webbing of the hand.
"A spang and a purlicue" was a measurement used when playing marbles (a 'spang' is the width of a belt buckle).
Etymology: Its origin is most often listed as the Scots word pirlie (twisted, having a tendency to curl up). Seen in dictionaries from the 1840s and later, and at least one reference from as far back as 1808.