Ullurai Uvamum

In Tamil literature, this is a way of alluding to something else than that which is specified in the poem. That is the meaning goes beyond the literary meaning (hidden meaning). A good example is what I found in the book "Smile of Murugan": (page 109).

" Look there my lord,
Near that lovely pond
With its broad green lotus leaves,
The heron
Motionless and without fear
Stands shining
Like a white and golden
Conch".

Heron is a white bird (naarai). Conch is sangu.

The above is a poem, a lady love tells her hero.

The first layer of meaning is the above.
The second layer of meaning comes from the fact that the bird stands motionless and without fear. When a heron stands motionless and without fear, it means no one is around. That is, the place is deserted.

The next layer of meaning that the author states in the book is that, the lady love indicates that the place is deserted, and hence is ideally suited for making love.

Thus, in the poem, the lady love, very elegantly and indirectly conveys her emotions to her lover. This is ullurai uvamum.  The other stunning part is the acute observation that the heron stands motionless and without fear only when there is no one around. How much they have observed nature!!