そっとsotto

1. adverbsoftly; gently; quietly; lightly
   彼女かのじょは子供こどもをそっと寝ねかせた。↗

   She laid the child down gently.
2. adverbstealthily; secretly; in secret
3. suru verbto leave alone; to leave as it isas 〜しておく

• SynonymこっそりNeutralDoing something stealthily so no one notices; the point is concealment. そっと can simply mean a light, gentle touch with no intent to hide.
• Synonym人知れずひとしれずNeutralWithout anyone knowing, as in 「人知れず涙を流す」; the emphasis is on going unnoticed. そっと stresses light movement.
• SynonymそろりCasualColloquial. Creeping or edging along slowly and carefully; the focus is slowness and caution. そっと is more general, covering secrecy and not disturbing others.
• RelatedふわりNeutralDescribes things drifting down, floating up, or settling softly over something. そっと is about a person deliberately making their movements light.
• RelatedふんわりNeutralDescribes a fluffy, soft, gentle feel, mostly texture or atmosphere. そっと is about light movements that don't disturb anyone.
• Related内々うちうちNeutralHandling something privately within a small circle, as in 「内々に済ませる」; the point is keeping it non-public. そっと stresses light or quiet action.
• Related穏やかおだやかNeutralA na-adjective for calm weather, mild temperament, or amicable attitudes. そっと is an adverb modifying actions, meaning gently or quietly.
• RelatedひっそりNeutralDescribes quiet, deserted places or living inconspicuously, as in 「ひっそり暮らす」; it paints places and states. そっと stresses light action.
• RelatedふわふわNeutralLight and floating, or fluffy and soft; it can also mean restless or frivolous. そっと is about a person moving quietly and doesn't describe texture.
• RelatedしずしずWrittenWritten style. Moving slowly with a dignified, stately air, as in 「静々と歩む」; そっと stresses light, quiet movement and carries no sense of formality.
• Related暗々のうちにあんあんのうちにWrittenWritten style. Doing something covertly, without others knowing; it says nothing about how light the action is. In everyday speech, use 「こっそり」.
• RelatedふわっとCasualColloquial. Floating up lightly or moving softly; it can also suggest an unsettled mind. そっと is about carefully making one's movements light.
• RelatedおもむろにWrittenWritten style. Beginning an action unhurriedly, sometimes with a deliberate, meaningful air; the emphasis is slowness. そっと stresses lightness and silence.
• Related密々みつみつWrittenWritten style and rare. Doing something secretly or privately; it says nothing about gentleness. In everyday speech, use 「こっそり」.
• Related心密かにこころひそかにWrittenWritten style. Secretly, within one's heart, as in 「心密かに願う」; it is limited to inner feelings, while そっと usually describes outward actions.
• Related陰ながらかげながらNeutralSupporting or praying for someone from behind the scenes, as in 「陰ながら応援する」; it is directed at others. そっと stresses light movement.
• Relatedお手柔らかにおてやわらかにNeutralA set polite phrase asking someone to go easy, as in 「お手柔らかにお願いします」; it is a courtesy formula, not a description of movement like そっと.
• RelatedやおらWrittenWritten style. Slowly and calmly beginning an action, and at times even suddenly. そっと stresses making no sound and not disturbing anyone.
• Antonym強くNeutralThe opposite in force: strongly or with pressure, as in 「強く押す」.
• Antonym激しくNeutralThe opposite in force and intensity: fiercely or violently, as in 「激しく叩く」.

Use 「そっと」 for light, quiet movement that doesn't disturb anyone; 「そっとしておく」 means to leave something or someone alone. For acting stealthily, pick 「こっそり」; for quiet, secluded places or living inconspicuously, 「ひっそり」; for things drifting or floating softly, 「ふわり」. 静々, 徐に, やおら, 暗々のうちに, 密々 and 心密かに are written-style; ふんわり, ふわふわ and ふわっと describe fluffiness or floating; 内々, 人知れず and 陰ながら stress secrecy or quiet support; お手柔らかに politely asks someone to go easy.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 静しずかに。
2. こっそり。密ひそかに。
3. そのままに。