Two words
May be 2 words combined (proto+dux) If not obvious, probably incorrect
dux N 3 1 NOM S M
dux N 3 1 VOC S M
dux, ducis N (3rd) M [XXXAX]
leader, guide; commander, general; Duke (medieval, Bee);
prot.o N 2 6 DAT S N
prot.o N 2 6 ABL S N
protos, proti N N [FXHEW] Medieval uncommon
first, foremost; best, top; initial; elementary; prime; (Greek);
prot.o ADJ 1 1 DAT S M POS
prot.o ADJ 1 1 DAT S N POS
prot.o ADJ 1 1 ABL S M POS
prot.o ADJ 1 1 ABL S N POS
protus, prota, protum ADJ [EXXEM] Later uncommon
first; original;
*

Credits:
This, our local install of the popular standby Whitaker's Words, is possible thanks to the resurrection of the venerable project at William Whitaker's Words, where you will also find extensive documentation. The corresponding GitHub repository is where you can submit issues about missing forms and analyses.
This web interface by Walter M. Shandruk.