Can I say "I (have) dropped the chair"?

If I accidentally pushed a chair and it fell down on the floor (it is no longer in the upright position), can I say "I (have) dropped the chair" or I should use another verb for that?

There are several verbs you can use to describe the action that was performed:

• tip over
• push over
• knock over
• knock down
• push down
• capsize (metaphorically)
• roll over
• fell (archaic, usually used with trees or foes)

Drop would only be accurate if it was held up and it fell down (as opposed to being up*right* and falling over).

The problem with drop here is that it implies you were holding it up in the first place and your action/inaction led to its falling to the floor. If you were involved in knocking over something which was free-standing in the first place, you can't use drop in a meaningful way (unless you had already pushed it halfway and were holding it up to prevent it falling completely).

No. A better statement is:

I (accidentally) pushed/knocked the chair over.

If you were carrying the chair from one end of the room to the other, and dropped it, you could use your statement.

The normal way to express this is to use the expression tip over:

When I leaned over too far backwards, I tipped the chair over.

The chair has a shaky leg, so be careful you don't tip it over.