upsetting

Concise Oxford English Dictionary © 2008 Oxford University Press:
upset

▶verb /ʌpˈsɛt/ (upsets, upsetting; past and past part. upset)

• 1 make unhappy, disappointed, or worried.

• 2 knock over.

• 3 disrupt.

  ■ disturb the digestion of (a person's stomach).

• 4 (often as noun upsetting) shorten and thicken the end or edge of (a metal bar, wheel rim, or other object).

▶noun /ˈʌpsɛt/ 

• 1 a state of being upset.

• 2 an unexpected result or situation.

▶adjective

• 1 /ʌpˈsɛt/ unhappy, disappointed, or worried.

• 2 /ˈʌpsɛt/ (of a person's stomach) having disturbed digestion.

– derivatives
upsetter noun,
upsetting adjective,
upsettingly adverb.