The operative word
Definition 1 of 2
Pro Tip 1/3Context Matters
The interpretation of 'the operative word' changes with context; identify what's most pivotal. 
If someone says, 'It's lightly raining,' the operative word is 'lightly.'
Pro Tip 2/3Emphasize Meaning
Use 'the operative word' to stress a particular aspect that shapes the overall meaning. 
In 'I will gladly assist,' the operative word is 'gladly' as it shows willingness.
Pro Tip 3/3Clarify Ambiguity
Highlight 'the operative word' to clarify meaning in ambiguous statements. 
'She might come' has the operative word 'might,' indicating uncertainty.