The adjectives brief and fleeting describe things of short duration. Used of events, brief can simply mean lasting a short time: a brief period, a brief meeting, a brief hello. Applied to speech and writing, brief suggests concise and effective: a brief introduction, a brief summary. Fleeting is used of things that pass quickly, with the suggestion that they escape our grasp or are over too soon: the fleeting pleasures of youth, fleeting fame, a fleeting thought, a fleeting glimpse. Fleeting can imply a poetic poignancy, but also fickleness, as in fleeting loyalties.
Waver and vacillate refer to an alternation or hesitation between one direction and another. A person who wavers pauses in the face of a choice, out of doubt or indecision: She lived at home for a year, wavering between college or a full-time job. Waver can refer to the weakening of something previously strong—faith, courage, or resolve may waver, but it doesn’t have a negative connotation. Vacillate, on the other hand, can imply ineffectiveness, weakness, or instability. A person who vacillates makes up their mind and changes it again suddenly, and then changes it back again, and so on (We’ll never get started unless you stop vacillating!). Minds, thoughts, and feelings typically vacillate, which can result in vacillating policies or poll numbers. However, if your emotions before a blind date vacillate between excitement and fear, no one will judge you.
Feast your eyes on these fun synonyms: party and fete. A party is a social gathering, as of invited guests at a private home, for conversation, refreshments, or entertainment: a cocktail party; a costume party. The more lavish synonym fete varies in meaning depending on context: a fete can be a festive celebration or entertainment (The ball was the greatest fete of the season!), a day of celebration of a holiday (The Fourth of July is a great American fete.), or a religious feast or festival (a fete lasting several days in honor of a saint). You may encounter the term spelled with a circumflex, fête, reflecting its French origins. July 14, Bastille Day, is often called la fête nationale in France.