1640s, "left, abandoned by the owner or guardian," from Latin derelictus "solitary, deserted," past participle of dereliquere "to abandon, forsake, desert," from de- "entirely" (see de-) + relinquere "leave behind, forsake, abandon, give up," from re- "back" (see re-) + linquere "to leave," from PIE root *leikw- "to leave."
Originally especially of vessels abandoned at sea or stranded on shore. Of persons, "unfaithful, neglectful of responsibility," by 1864. As a noun, "property which is abandoned," from 1660s. As "person abandoned or forsaken," 1728.
1590s, "abandonment, state of being forsaken or abandoned" (formerly with a wider range than in modern use, such as of the sea withdrawing from the land), from Latin derelictionem (nominative derelictio) "an abandoning; a disregarding, neglecting," noun of action from past-participle stem of derelinquere (see derelict).
Sense of "act of leaving with an intention not to reclaim or reuse" is from 1610s. Meaning "failure, unfaithfulness, neglect" (with regard to duty, etc.) is by 1778. Phrase dereliction of duty attested from 1776.
Proto-Indo-European root meaning "to leave."
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit reknas "inheritance, wealth," rinakti "leaves;" Greek leipein "to leave, be lacking;" Latin linquere "to leave;" Gothic leihvan, Old English lænan "to lend;" Old High German lihan "to borrow;" Old Norse lan "loan."