vermiesen
to spoil
To spoil someone's enjoyment of something, good mood, or plan. A colloquial expression.
Lass dir von dem schlechten Wetter doch nicht den ganzen Ausflug vermiesen!
Don't let the bad weather spoil the whole trip for you!

to spoil
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to spoil
To spoil someone's enjoyment of something, good mood, or plan. A colloquial expression.
Lass dir von dem schlechten Wetter doch nicht den ganzen Ausflug vermiesen!
Don't let the bad weather spoil the whole trip for you!

The verb is made up of the prefix 'ver-' and the adjective 'mies' (bad, nasty). So it literally means to 'make something bad' or to spoil it.
Seine schlechte Laune hat allen den Abend vermiest.
His bad mood spoiled the evening for everyone.
This verb follows a fixed pattern: The person whose enjoyment is spoiled is always in the dative. The thing that is spoiled is in the accusative: Jemand vermiest jemandem (dative) etwas (accusative).
Der Regen hat uns (Dativ) den Ausflug (Akkusativ) vermiest.
The rain spoiled the trip (accusative) for us (dative).
'Vermiesen' is a colloquial word. It is used less often in formal or written contexts.
Komm schon, vermies mir nicht die gute Laune!
Come on, don't spoil my good mood!
Abstract things related to enjoyment and well-being are often 'vermiest' (spoiled). Typical phrases are: jemandem die Laune vermiesen (to spoil someone's mood), den Spaß vermiesen (to spoil the fun), den Appetit vermiesen (to spoil the appetite), or den Tag vermiesen (to spoil the day).
Die unerwartete Arbeit hat ihm das ganze Wochenende vermiest.
The unexpected work spoiled his whole weekend.
to spoil / ruin
'verderben' and 'vermiesen' can both express that someone's enjoyment, good mood, or a nice moment is taken away. 'verderben' is more neutral and can be used in many situations. 'vermiesen' is more colloquial and sounds more personal: someone or something makes something unpleasant for you. In conversations with friends, 'vermiesen' often sounds natural. In more neutral texts or more serious situations, 'verderben' fits better.

Lass dir den freien Tag nicht von einer schlechten Nachricht vermiesen.
Don't let a piece of bad news spoil your day off.
Der Regen hat die Stimmung beim Ausflug ein wenig verdorben.
The rain spoiled the mood on the outing a little.