Collocations for calm - adj.

appear, be, feel, look, seem, sound
I may have appeared calm but I certainly didn''t feel it.

become | keep, remain, stay
Sit down and keep calm! | The pilot urged the passengers to remain calm.

keep sb
Keep the patient calm.

extremely, remarkably, very
You seem remarkably calm.

completely, perfectly, utterly
Her voice was firm and perfectly calm.

fairly, pretty, quite | apparently, outwardly | curiously, strangely
The pain had receded and he felt curiously calm.

reassuringly
The voice sounded reassuringly calm.

about
She seemed pretty calm about it.

cool, calm and collected
He remained at all times cool, calm and collected.

be, look | become

absolutely, dead, flat, perfectly
The sea was dead calm. | flat calm conditions

fairly, quite, relatively