(adj) associated by chance and not an integral part; - Frederick W. Robertson, Example:poetry is something to which words are the accidental, not by any means the essential form; they had to decide whether his misconduct was adventitious or the result of a flaw in his character

adventitious root

(n) root growing in an unusual location e.g. from a stem

adventive

(adj) not native and not fully established; locally or temporarily naturalized, Example:an adventive weed

advent sunday

(n) the first of the four Sundays during Advent

adventure

(n) a wild and exciting undertaking (not necessarily lawful), Syn. dangerous undertaking, risky venture, escapade

The Collaborative International Dictionary of English (GCIDE) v.0.53 Collaborative International Dictionary (GCIDE)

Advent

n. [ L. adventus, fr. advenire, adventum: cf. F. avent. See Advene. ] 1. (Eccl.) The period including the four Sundays before Christmas. [ 1913 Webster ]

Advent Sunday (Eccl.), the first Sunday in the season of Advent, being always the nearest Sunday to the feast of St. Andrew (Now. 30). Shipley. [ 1913 Webster ]

2. The first or the expected second coming of Christ. [ 1913 Webster ]

3. Coming; any important arrival; approach. [ 1913 Webster ]

Death's dreadful advent. Young. [ 1913 Webster ]

Expecting still his advent home. Tennyson. [ 1913 Webster ]

Adventism

n. 1. 1 any Christian religion that believes the second coming of Christ is imminent.
Syn. -- Second Adventism [ WordNet 1.5 ]

Adventist

n. One of a religious body, embracing several branches, who look for the proximate personal coming of Christ; -- called also Second Adventists. Schaff-Herzog Encyc. [ 1913 Webster ]

adventitia

n. 1. the membranous outer covering of an organ or blood vessel. [ WordNet 1.5 ]

adventitial

adj. 1. of or pertaining to adventitia. [ WordNet 1.5 ]

adventitious

a. [ L. adventitius. ] 1. Added extrinsically; not essentially inherent.
Syn. -- accidental; casual; incidental; additional; supervenient; foreign. [ 1913 Webster + PJC ]

To things of great dimensions, if we annex an adventitious idea of terror, they become without comparison greater. Burke. [ 1913 Webster ]

2. (Nat. Hist.) Out of the proper or usual place; as, adventitious buds or roots. [ 1913 Webster ]

3. (Bot.) Accidentally or sparingly spontaneous in a country or district; not fully naturalized; adventive; -- applied to foreign plants. [ 1913 Webster ]

4. (Med.) Acquired, as diseases; not hereditary. AS [ 1913 Webster ]

5. (Med.) Occurring in an unusual place or arising from an external source. Stedman 25 [ PC ]

-- Ad`ven*ti"tious*ly, adv. -- Ad`ven*ti"tious*ness, n. [ 1913 Webster ]

Adventive

n. A thing or person coming from without; an immigrant. [ R. ] Bacon. [ 1913 Webster ]

Adventive

a. 1. Accidental. [ 1913 Webster ]

2. (Bot.) Adventitious. Gray. [ 1913 Webster ]

Adventual

a. Relating to the season of advent. Sanderson. [ 1913 Webster ]

Adventure

v. i. To try the chance; to take the risk. [ 1913 Webster ]