1650s, originally theological, "matters of practice," as opposed to credenda "things to be believed, matters of faith," from Latin agenda, literally "things to be done," neuter plural of agendus, gerundive of agere "to do" (from PIE root *ag- "to drive, draw out or forth, move").

The modern sense of "items of business to be done at a meeting" is attested by 1882. "If a singular is required (=one item of the agenda) it is now agendum, the former singular agend being obsolete" [Fowler].

"Spanish nobleman of secondary rank," 1590s, from Spanish hidalgo, from Old Spanish fidalgo, usually explained as a shortened from filho de algo "son" (Latin filius, see filial) "of someone" (Latin aliquis, ultimately from PIE root *al- "beyond" + PIE pronomial root *kwo-); this is perhaps an imitation of Arabic ibn-nas "son of people," a complimentary title. For alteration of f- and h- in Spanish, see hacienda.

sea-storm of severest intensity, 1550s, a partially deformed adoption of Spanish huracan (Gonzalo Fernandez de Oviedo y Valdés, "Historia General y Natural de las Indias," 1547-9), furacan (in the works of Pedro Mártir De Anghiera, chaplain to the court of King Ferdinand and Queen Isabella and historian of Spanish explorations), from an Arawakan (West Indies) word. In Portuguese, it became furacão. For confusion of initial -f- and -h- in Spanish, see hacienda. The word is first in English in Richard Eden's "Decades of the New World":

These tempestes of the ayer (which the Grecians caule Tiphones ...) they caule furacanes.

OED records 39 different spellings, mostly from the late 16c., including forcane, herrycano, harrycain, hurlecane. The modern form became frequent from 1650 and was established after 1688. Shakespeare uses hurricano ("King Lear," "Troilus and Cressida"), but in reference to waterspouts.

*dhē-, Proto-Indo-European root meaning "to set, put."

It might form all or part of: abdomen; abscond; add; affair; affect (v.1) "make a mental impression on;" affect (v.2) "make a pretense of;" affection; amplify; anathema; antithesis; apothecary; artifact; artifice; beatific; benefice; beneficence; beneficial; benefit; betray; bibliothec; bodega; boutique; certify; chafe; chauffeur; comfit; condiment; confection; confetti; counterfeit; deed; deem; deface; defeasance; defeat; defect; deficient; difficulty; dignify; discomfit; do (v.); doom; -dom; duma; edifice; edify; efface; effect; efficacious; efficient; epithet; facade; face; facet; facial; -facient; facile; facilitate; facsimile; fact; faction (n.1) "political party;" -faction; factitious; factitive; factor; factory; factotum; faculty; fashion; feasible; feat; feature; feckless; fetish; -fic; fordo; forfeit; -fy; gratify; hacienda; hypothecate; hypothesis; incondite; indeed; infect; justify; malefactor; malfeasance; manufacture; metathesis; misfeasance; modify; mollify; multifarious; notify; nullify; office; officinal; omnifarious; orifice; parenthesis; perfect; petrify; pluperfect; pontifex; prefect; prima facie; proficient; profit; prosthesis; prothesis; purdah; putrefy; qualify; rarefy; recondite; rectify; refectory; sacrifice; salmagundi; samadhi; satisfy; sconce; suffice; sufficient; surface; surfeit; synthesis; tay; ticking (n.); theco-; thematic; theme; thesis; tradition; traitor; verify.

It might also be the source of: Sanskrit dadhati "puts, places;" Avestan dadaiti "he puts;" Old Persian ada "he made;" Hittite dai- "to place;" Greek tithenai "to put, set, place;" Latin facere "to make, do; perform; bring about;" Lithuanian dėti "to put;" Polish dziać się "to be happening;" Russian delat' "to do;" Old High German tuon, German tun, Old English don "to do."