fair, good, reasonable, safe
April is the best guess for first deliveries.

calculated, educated, informed, inspired, intelligent
As a vet, he could make an educated guess as to what was wrong with his stomach.

rough, wild
At a rough guess, I''d say we''re about twenty miles from home.

lucky
‘How did you know?’‘It was just a lucky guess.’

have, hazard, make, take
If you don''t know the answer, have a guess. | If I might hazard a guess …

give sb
‘Where''s Tom?’ ‘I''ll give you three guesses!’ (= the answer is fairly obvious and you should guess it easily)

at a ~
At a guess, I''d say there''s a problem with the fuel pump.

~ about/as to/at
He made a wild guess as to how much the piano might cost.

correctly, right | incorrectly, wrong
Jane had guessed wrong about who was responsible for the fire.

never
You''ll never guess what she told me.

can/could
Can you guess his age?

can only
We can only guess how fast a dinosaur might have run.

try to | be easy to, not be difficult to, not be hard to
It''s not hard to guess where they went.

at
I was only guessing at her age.

from
She guessed from his expression that he had not won.

could/might/should have guessed
So it was Rob who broke the window? I might have guessed!

let me guess
What star sign are you? No, let me guess.