having an acid taste, resembling that of vinegar, lemon juice, etc.; tart.

rendered acid or affected by fermentation; fermented.

producing the one of the four basic taste sensations that is not bitter, salt, or sweet.

characteristic of something fermented

a sour smell.

distasteful or disagreeable; unpleasant.

below standard; poor.

harsh in spirit or temper; austere; morose; peevish.

Agriculture . (of soil) having excessive acidity.

(of gasoline or the like) contaminated by sulfur compounds.

Music . off-pitch; badly produced

a sour note.

something that is sour.

any of various cocktails consisting typically of whiskey or gin with lemon or lime juice and sugar and sometimes soda water, often garnished with a slice of orange, a maraschino cherry, or both.

an acid or an acidic substance used in laundering and bleaching to neutralize alkalis and to decompose residual soap or bleach.

to become sour, rancid, mildewed, etc.; spoil

Milk sours quickly in warm weather. The laundry soured before it was ironed.

to become unpleasant or strained; worsen; deteriorate

Relations between the two countries have soured.

to become bitter, disillusioned, or disinterested

I guess I soured when I learned he was married. My loyalty soured after his last book.

Agriculture . (of soil) to develop excessive acidity.

to make sour; cause sourness in

What do they use to sour the mash?

to cause spoilage in; rot

Defective cartons soured the apples.

to make bitter, disillusioned, or disagreeable

One misadventure needn't have soured him. That swindle soured a great many potential investors.