The uniting word is

RAINBOW!!!

Because

Each of these clue a different 7 character word:

1. A GRANMA = anagram of 'ANAGRAM'
2. TO BE PAID = 'PAYABLE'
3. MACHINE-LIKE = 'ROBOTIC'
4. LIVE AGAIN (LINGUA MEA) = latin for 'RE-VIVE'

Giving this squaare:

ANAGRAM
PAYABLE
ROBOTIC
RE-VIVE

Now

If we compare these to the dots and consider the letters where there are no dots, we get:

G
Y B
O I
R V

(Note I think last line should be the 6th space missing, not the 7th to give 'V', unless its not 're-vive')

This is

ROYGBIV - the colours of the rainbow, in the shape of a bow!

In fact, treating the dots as raindrops, it literally forms a bow in the rain!

So the uniting word is

RAINBOW!!!

The uniting word is

RAINBOW!!!

Because

Each of these clue a different 7 character word:

1. A GRANMA = anagram of 'ANAGRAM'
2. TO BE PAID = 'PAYABLE'
3. MACHINE-LIKE = 'ROBOTIC'
4. LIVE AGAIN (LINGUA MEA) = latin for revive = ‘REDIVIV’

Giving this squaare:

ANAGRAM
PAYABLE
ROBOTIC
REDIVIV

Now

If we compare these to the dots and consider the letters where there are no dots, we get:

G
Y B
O I
R V

This is

ROYGBIV - the colours of the rainbow, in the shape of a bow!

In fact, treating the dots as raindrops, it literally forms a bow in the rain!

So the uniting word is

RAINBOW!!!