leading (adj.) Look up leading at Dictionary.com
1590s, "that goes first," present participle adjective from lead (v.1). Meaning "directing, guiding" is from 1620s. Of persons, "having first or most prominent place," 1670s. Leading lady in a theatrical company is from 1874; leading man from 1885.
leading (n.2) Look up leading at Dictionary.com
mid-13c., "a bringing by force," verbal noun from lead (v.1). Meaning "direction, guidance" is from late 14c.
leading (n.1) Look up leading at Dictionary.com
"lead work; lead covering or frame of lead," mid-15c., verbal noun from lead (n.1). Printing sense is from 1855.