ADJ

lengthy, long, prolonged
brief, momentary, a moment's, short
There was a moment's silence before she replied
deep, hushed
absolute, complete, dead, deadly, deathly, total, utter
We sat in complete silence, save for the ticking of the clock. A deathly silence hung over the town
shocked, stunned
awkward, embarrassed, embarrassing, strained, uncomfortable
An awkward silence followed
fraught, heavy, ominous, tense
brooding
She fell into long, brooding silences
stony, sullen
eerie
companionable
They walked in companionable silence
expectant, pregnant
sudden

VERB + SILENCE

maintain
She maintained a stony silence
break, interrupt, punctuate, shatter
Lewis finally broke the long silence between them. a silence punctuated only by the occasional sniff from the children
lapse into, relapse into, retreat into, subside into, trail into (all only used about people)
He lapsed into a sullen silence
stun sb into
The boys were stunned into silence by this news
be met with
Her question was met with an uneasy silence
observe (= as a sign of respect for the dead, etc.)
A minute's silence for the victims will be observed

SILENCE + VERB

descend, fall
A sudden silence fell over the room
hang, prevail, reign
Silence reigned
ensue, follow
deepen, grow, lengthen, spread, stretch
He thought for a moment, the silence lengthening

PREP

in (the) ~
They ate their breakfast in silence

ADJ

deafening
The government's only response has been a deafening silence
dignified
deliberate

VERB + SILENCE

keep, maintain
He has so far kept a dignified silence on the subject

PREP

~ from
There seems to have been a deliberate silence from the newspapers

PHRASES

a conspiracy/wall of silence
There is a conspiracy of silence about what is happening (= nobody is willing to talk about it)
the right to silence (= the right not to say anything when accused of a crime), a vow of silence
She has broken her vow of silence on the issue