What's the difference between อายุมาก, แก่ and เก่า? As far as I can tell, they all mean "old".

Can they be used interchangeably?

Thanks!

The first two can only be used in reference to living beings; the third one can only be used in reference to inanimate objects or abstract concepts.

The first may be a little more polite. A little like how in the west we say Aged Care not Old Care. Not much in it though.

อายุมาก http://www.thai2english.com/dictionary/1454239.html

แก่ http://www.thai2english.com/dictionary/1274175.html

เก่า http://www.thai2english.com/dictionary/1273639.html

สูงอายุ - ถูกตอง

http://www.thai2english.com/dictionary/1409322.html

The polite option here is สูงอายุ.

อายุมาก isn't particularly common.

The first two can only be used in reference to living beings; the third one can only be used in reference to inanimate objects or abstract concepts.

I thought it is fairly common to refer to an ex-boy or girlfriend as แฟนเก่า

The first two can only be used in reference to living beings; the third one can only be used in reference to inanimate objects or abstract concepts.

I thought it is fairly common to refer to an ex-boy or girlfriend as แฟนเก่า

Yes, but old doesn't mean "old age" here, it mean "ex" or "previous". In that context เก่า can be used with people.

Although all those words mean "old" in English, they all have slightly different meanings in Thai.

อายุมาก and แก่ means "old (age)" and is used for living things such as people and animals. อายุมาก is more polite than แก่ so for those who are unsure, always stick to อายุมาก to be on the safe side.

เก่า means "old" as in "opposite of new" so this can be used with anything (including living things) to mean such as former/previous or something which is not new. Such as your old car, รถคันเก่า, ex-wife เมียเกา

Then there's เก่าแก่ which also means "old age" but is used for non-living things and plants, such as veteran car รถเก่าแก่ or old tree ต้นไม้เก่าแก่

โบราณ is used for something very old (ancient) such as antiques วัตถุโบราณ

Thanks for the feed back.