this is a.....um..what?  

A candle holder....
surely? Nice shape.

doorstop ?
I once had a pair of georgian door stops and this reminds me of them....who knows.

would make
a wonderful club. Weighs about 5 lbs.
handsome though, whatever it is.

diFrutta?
Has elements of a Gianni Sacco diFrutta - the longish bulbous shape at the end. But 18" is rather ambitious - even for diFrutta.

oh, that's easy
It is a Teak Object.

looks like lamp base
looks like lamp base

no
no place for wiring. I thought the same thing
I am leaning towards giant candleholder.

.
Maybe someone wanted to make a mallet and ended up just having a play on the lathe, have a few things around here that are just the results of seeing what happens, nice forms without a practical use.

If you had...
a Danish teak pestal, you could use this mortar to mash up some rock cocaine and the whole forum could stay up all night long trying to think of other uses.

No doubt
about it....it's an "um..what", alright. And a nice one too.

Who knows
and maybe not, but i have a few of these i found in my 1880's saltbox.
All different sizes with anything goes turning designs.
They are potato/vegetable mashers. It is a small fishing village and they all
seem to use them. If it is, i'm just guessing the curve at the base is a clever
design to accommodate the bowl shape.
If apothecary, or for spices, i would think it would be ceramic.
If for woodworking, it should have some tap damage.
If for stitching, that is one big darn sock.

I thought that
when i picked it up. but
no damage from being used as a smasher/grinder of some type
and
the hole in the top would have made the handle fragile, the walls would have been too thin for much violence.
Object d' whatever