What is a DB-cursor?

1) A reference to an element at a specific position in a data structure. (2) A database control structure used to point to a specific row within some ordered set of rows, and to retrieve rows from a set, in order to make updates or deletions.
scv.bu.edu/SCV/Archive/IBM/BGL/compiler/xlc-8.0/html/glossary/czgc.htm

2) Cursors are pointers used to fetch rows from a result set. One can think of a cursor as a data structure that describes the results returned from a SQL SELECT statement. One of the variables in this structure is a pointer to the next record to be fetched from the query results.
orafaq.com/glossary/faqglosc.htm

3) In database packages, the term cursor refers to a control structure for the successive (and potential processing) of records in a result set.
en.wikipedia.org/wiki/Cursor (databases)