| simulated(extra, auxiliary, supernumerary) |
| small-fry(reserve, subsidiary, supportive) |
| small fry(expression, reserve, subsidiary, supportive) |
| small time(expression, reserve, subsidiary, supportive) |
| spare(reserve, subsidiary, supportive) |
| spurious(extra, auxiliary, supernumerary) |
| standby(reserve, extra, subsidiary, auxiliary, supernumerary) |
| stopgap(extra, auxiliary, supernumerary) |
| subsidiary(reserve, supportive) |
| substract(reserve, subsidiary, supportive) |
| supernumerary(extra, auxiliary) |
| supplemental(extra, auxiliary, supernumerary) |
| supplementary(extra, auxiliary, supernumerary) |
| supporting(reserve, subsidiary, supportive) |
| supportive(reserve, subsidiary) |
| supposititious(extra, auxiliary, supernumerary) |
| surrogate(extra, auxiliary, supernumerary, back-up, flipside) |
| symbolic(extra, auxiliary, supernumerary) |
| temporary(extra, auxiliary, supernumerary) |
| tentative(extra, auxiliary, supernumerary) |