umkippen
to tip over
To fall sideways from an upright position; to lose balance and fall over.
Pass auf, dass das Glas auf dem wackeligen Tisch nicht umkippt.
Be careful that the glass on the wobbly table doesn't tip over.

to tip over / faint
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to tip over
To fall sideways from an upright position; to lose balance and fall over.
Pass auf, dass das Glas auf dem wackeligen Tisch nicht umkippt.
Be careful that the glass on the wobbly table doesn't tip over.

'Umkippen' (to tip over / faint) is a separable verb. The prefix 'um-' goes at the end in a main clause. In subordinate clauses and in the infinitive with 'zu', the verb stays together.
Der starke Wind kippte mehrere Bäume um.
The strong wind tipped several trees over.
The perfect tense of 'umkippen' (to tip over / faint) is always formed with the auxiliary verb 'sein' because it describes a change of state or position. So it is 'ist umgekippt'.
Das volle Wasserglas ist plötzlich umgekippt.
The full water glass suddenly tipped over.
You can recognize the meaning from the subject: If the subject is an object, it falls over. If it is a person, they faint. If it is something abstract like 'Stimmung' (mood) or 'Wetter' (weather), it changes for the worse. If it is a body of water, the ecosystem collapses.
Der Radfahrer ist in der Kurve fast umgekippt.
The cyclist almost tipped over on the bend.
In the meaning 'ohnmächtig werden' (to faint), 'umkippen' (to faint) is rather colloquial. It is often used in spoken language to describe a sudden loss of consciousness.
Als er das Blut sah, ist er sofort umgekippt.
When he saw the blood, he fainted immediately.
to fall
'fallen' and 'umkippen' can both describe something moving downward and no longer being stable. 'fallen' is the general word for a downward movement. 'umkippen' is used when something was previously upright or balanced and then tips to the side, for example a glass, a bicycle, or a person. With people, 'umkippen' can also mean that someone suddenly faints. The words can be confused because the result looks similar. If the sideways tipping movement is important, 'umkippen' fits better; otherwise, 'fallen' is more general.

Wegen der Hitze kippt Ben bei der Arbeit fast um.
Because of the heat, Ben almost faints at work.
Ein Apfel fällt vom Baum direkt vor meine Füße.
An apple falls from the tree right in front of my feet.