Definition of "lah"

lah¹

/lɑ/

noun
plural lahs
1. (music) Alternative spelling of la

lah²

/lɑː˨/

particle
1. Placed at the end of a sentence to accentuate the mood or attitude of the speaker.
  Quotations
  Don’t know lah […] this is very hard to say.
  1978, Leong Choon Cheong, Youth in the Army, Singapore: Federal Publications, page 75
2. Placed at the end of a sentence to convey reassurance or solidarity.
  Quotations
  Don’t worry lah. We’ll meet the deadline.
  1999, Alfian Sa'at, Corridor, Singapore: SNP Editions, page 15
3. Asserts that something is clear or straightforward.
4. Used to tone down an imperative sentence.
5. Reinforces an assertion.
6. (rarer) Follows each item in a list of examples.
  Quotations
  He teach them how to cook lah, learn computer lah... […]
  2010, Haresh Sharma, Those Who Can't, Teach, Epigram Books, Act I, scene ii
7. (in fixed expressions) Used sarcastically when stating the obvious.