Short answer
There is no fixed meaning. The classical dream interpreters often read a snake as an enemy, its size and strength showing how dangerous that enemy is, and killing it as overcoming him. But a frightening dream may simply come from Shaytan or your own worries. If it scared you, seek refuge in Allah and do not tell people about it.
Dream interpretation is not a source of rulings, and nobody may act on a dream against the Shariah. A good dream may be told to a wise and caring person. For a bad dream, the sunnah is to seek refuge in Allah, spit lightly to the left three times, turn over, and not narrate it.
The four schools agree on this.
Explanation
The Prophet ﷺ said dreams are of three kinds: a true dream that is good news from Allah, a dream in which Shaytan tries to frighten you, and a dream made of your own thoughts during the day. Most snake dreams people search about are frightening, so they usually belong to the second or third kind.
For a bad dream, the sunnah gives clear steps:
- Seek refuge in Allah from Shaytan and from the evil of the dream.
- Spit lightly, without saliva, to your left three times.
- Turn over onto your other side.
- Do not tell people about it. The Prophet ﷺ said that if you do this, it will not harm you.
- If you wish, get up and pray.
As for the snake itself, the dream manuals, such as the one attributed to Ibn Sirin, usually read it as an enemy. A large snake points to a strong enemy, killing it to victory over him, and a bite to harm from him. These are possible readings by people who studied dreams, not certain knowledge. Only the dreams of prophets are revelation. The Prophet ﷺ said a dream is like something on a bird's leg until it is interpreted, so take it only to someone knowledgeable who wishes you well, or to nobody.
Be careful with online dream dictionaries and with people who charge money to interpret dreams. Do not let a dream make you suspicious of family or friends. More in Dreams in Islam.
The evidence
Quran, Surah Yusuf 12:5
قَالَ يَٰبُنَىَّ لَا تَقْصُصْ رُءْيَاكَ عَلَىٰٓ إِخْوَتِكَ فَيَكِيدُوا۟ لَكَ كَيْدًا ۖ إِنَّ ٱلشَّيْطَٰنَ لِلْإِنسَٰنِ عَدُوٌّۭ مُّبِينٌۭ ﴿٥﴾
He said, "O my son, do not relate your vision to your brothers or they will contrive against you a plan. Indeed Satan, to man, is a manifest enemy.
Yaqub told Yusuf not to share his dream, showing that dreams are not to be told to everyone.
Sahih Muslim 2263
Sahih... الرؤيا ثلاثة فرؤيا الصالحة بشرى من الله ...
"Dreams are of three kinds: a good dream is glad tidings from Allah."
Not every dream has a meaning from Allah.
Sahih Muslim 2262
Sahih... فليبصق عن يساره ثلاثا وليستعذ بالله من الشيطان ثلاثا ...
"Let him spit to his left three times and seek refuge in Allah from Shaytan three times."
The sunnah steps after a bad dream.
Sunan Abi Dawud 5020
Graded sahih... الرؤيا على رجل طائر ما لم تعبر ...
"A dream is on the leg of a bird as long as it is not interpreted."
Only share dreams with someone wise and caring.
Where the ruling is recorded
- Fath al-Bari (Ibn Hajar), Kitab al-Ta'bir. Explains the kinds of dreams, the etiquette after them, and the limits of interpretation.
This answer is pending review by the scholars on our team. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.