proto-proto- /prəʊtəʊ, -tə $ proʊtoʊ, -tə/ prefix 
technical existing or coming before other things of the same type: 
a proto-fascist group a prototype
technical existing or coming before other things of the same type: a proto-fascist group a prototype- secession
- secessionist
- secluded
- seclusion
- second
- Second Advent
- secondarily
- secondary
- secondary modern
- secondary school
- secondary source
- secondary stress
- second base
- second best
- second childhood
- second class
- second-class
- Second Coming
- second-degree
- seconder
- second-guess
- Second Gulf War
- second hand
- second-hand
- second home