(1) (Pulse Amplitude Modulation) The conversion of audio wave samples to pulses (voltages). PAM is the first step in pulse code modulation (PCM), which is followed by converting the pulses to digital numbers. See PCM.

(2) (Pluggable Authentication Modules) A programming interface that enables third-party security methods to be used in Unix. For example, smart cards, Kerberos and RSA technologies can be integrated with various Unix functions such as rlogin, telnet and ftp.