drop in

To visit someone without arranging it beforehand, usually for a short time.

• Drop in whenever you like.
• My cousin dropped in yesterday.
• Shall we drop in on Anna after lunch?

How to use it: drop in on someone (We dropped in on my aunt.); drop in at somewhere (I dropped in at the office.); drop in for something (Drop in for tea if you have time.)

Similar words: drop by, stop by, pop in

Common phrases: drop in anytime, drop in on someone, drop in for coffee

To fall, or let something fall, into a container or space.

• Drop a coin in the box.
• My keys dropped in the pond.
• He dropped the vegetables in the boiling water.

How to use it: drop something in something (She dropped a coin in the jar.)

Similar words: fall into, put into

Common phrases: drop in something, drop something in

To put a new part into a machine, especially an engine into a car.

• We can drop in a new engine.
• The mechanic dropped a replacement motor in yesterday.
• They dropped in better parts before the race.

How to use it: drop something in (The mechanic dropped a new motor in.); drop in something (They dropped in a replacement engine.)

Similar words: install, fit

Opposites: remove

Common phrases: drop in an engine, drop in new parts

To start surfing on a wave that another surfer is already riding.

• That surfer dropped in on me.
• Never drop in when someone else has the wave.
• She apologized for dropping in on another rider.

How to use it: drop in on someone (Do not drop in on a surfer already riding the wave.)

Common phrases: drop in on someone, drop in while surfing

To fall inward because something is no longer strong enough to hold its shape.

• The roof dropped in.
• We feared the ceiling would drop in during the storm.
• Rotten supports caused part of the tunnel to drop in.

Similar words: cave in, collapse

Common phrases: roof may drop in, ceiling could drop in