The word "safe" is widely used in everyday education speak in phrases such as "safe learning environment", but how do trainee and experienced teachers interpret, understand and use this word in their everyday teaching? Teachers are acting as observers of pupils' well-being, and one of their roles in the classroom is to offer support to build relationships and enable pupils to achieve their best. This case study reports the use of the "safe" concept by trainee and experienced teachers in England and uses "safe spaces" groupings to allow categorising of the qualitative results obtained. The majority of trainee teacher responses related to "safe" meaning a classroom where no child is embarrassed about sharing their opinions/answers, where pupils are comfortable about taking risks in their learning and one which is rooted in mutual respect. Experienced teachers reported that a "safe" classroom was where pupils could express their thoughts, feel comfortable and be safe from harm. This concept has been used by all participants in this study but differently. The findings could help develop teachers' understandings to ensure the use of the word "safe" is not limited and maximum impact within school is obtained. It could help all teachers to be fully aware of the broadness of the concept, especially that surrounding the ability to achieve due to the importance of feeling safe in lessons.