honorarium(n = noun.possession) - a fee paid for a nominally free service;
is a kind of reward
1. A fee offered to professional men for their services; as, an honorarium of one thousand dollars. S. Longfellow. [1913 Webster]
2. An honorary payment, usually in recognition of services for which it is not usual or not lawful to assign a fixed business price. Heumann. [1913 Webster]
honorarium, n. (pl. honorariums or honoraria) a fee, esp. a voluntary payment for professional services rendered without the normal fee.
Etymology:
L, neut. of honorarius: see HONORARY
N giving, bestowal, bestowment, donation, presentation, presentment, accordance, concession, delivery, consignment, dispensation, communication, endowment, investment, investiture, award, almsgiving, charity, liberality, generosity, gift, donation, present, cadeau, fairing, free gift, boon, favor, benefaction, grant, offering, oblation, sacrifice, immolation, lagniappe, pilon, grace, act of grace, bonus, allowance, contribution, subscription, subsidy, tribute, subvention, bequest, legacy, devise, will, dotation, dot, appanage, voluntary settlement, voluntary conveyance, amortization, alms, largess, bounty, dole, sportule, donative, help, oblation, offertory, honorarium, gratuity, Peter pence, sportula, Christmas box, Easter offering, vail, douceur, drink money, pourboire, trinkgeld, bakshish, fee, consideration, bribe, bait, ground bait, peace offering, handsel, boodle, graft, grease, blat, giver, grantor, donor, feoffer, settlor, giving, given, allowed, allowable, concessional, communicable, charitable, eleemosynary, sportulary, tributary, gratis, donative, auctor pretiosa facit, ex dono, res est ingeniosa dare.
N reward, recompense, remuneration, meed, guerdon, reguerdon, price, indemnity, indemnification, quittance, compensation, reparation, redress, satisfaction, reckoning, acknowledgment, requital, amends, sop, atonement, retribution, consideration, return, quid pro quo, salvage, perquisite, vail, douceur, bribe, hush money, smart money, blackmail, extortion, carcelage, solatium, allowance, salary, stipend, wages, compensation, pay, payment, emolument, tribute, batta, shot, scot, bonus, premium, tip, fee, honorarium, hire, dasturi, dustoori, mileage, crown, remunerative, remuneratory, munerary, compensatory, retributive, reparatory, rewarding, satisfactory, fideli certa merces, honor virtutis praemium, tibi seris tibi metis.