tight-lipped · mute · whisper · shush · confidential · discreet · unspoken · sworn · closemouthed · buttoned up · wordless · tongue-tied · hushed · cagey · evasive · private · guarded · reticent
IDEA.org / Words / keeps mum
Related — silent (Producing no sound); hush (Absence of sound); quiet (Lacking in sound); secret · lips sealed · tight-lipped · mute · whisper · shush · confidential · discreet · unspoken · sworn
verbal disclosurekeeps mum ≠ spills the beans Divulges confidential information; tells all · blabs · reveals · discloses · divulges
communication stylekeeps mum ≠ chatters Talks fast, trivially; gabs · overshares · gossips · prattles · babbles
emotional expressivenesskeeps mum ≠ vents Openings for airflow; emotes · explodes · unloads · gushes · sounds off
staying silent: hushes, shuts up
Word data: Linguabase (CC0) · www.idea.org/words/keeps_mum