Monotonous comes from Greek "monotonos". Greek "monotonos" is a compound made from the word "monos" which means single and "tonos", pitch, key, or musical scale in which a piece of music is composed.

Monotonous means, dull because of being always the same.

The old English spelling of the word was "ūtlendisc". The sound (sh) was spelled "sc" in old English times. In Old English "ūtland", literally "out-land", meant "foreign country".

Outlandish means, unconventional or strange.

Vigilant comes from the Latin word "vigiāns", the present participle of the Latin verb "vigilāre", which means "to be watchful".

Vigilant means, watching out for danger or something that might go wrong; watchful.

The English word meticulous originally meant "fearful". Because a person who is fearful of making a mistake will take great care while performing a task, meticulous came to mean "extremely careful". It comes from the Latin word "metīculōsus, "fearful".

Meticulous means, showing great concern for details; extremely careful or precise.

Furtive comes from the Latin word "furtīvus", which can mean both "obtained by theft" and "stealthy"."Furtīvus" is related to the Latin words "furtum", theft and "fur", thief.

Furtive means, done or acting in a way that is intended not to be seen.

It comes from the Latin adjective "cōnspicuus. Cōnspicuus comes from the word cōnspicere. Cōn meaning "throughly" and specere "easy to see".

Conspicuous means, easily seen; obvious. Attracting attention; striking; remarkable.

Egregious comes from Latin "ēgregious", standing out. Latin "ēgregious" itself is made up of the Latin prefix ē- (the form that the prefix ex-, "out", takes before consonants), and greg-, a form of the Latin word grex, "herd".

Egregious means, well beyond the bound of what is right or proper; outrageous.

Apprehensive comes from the Latin verb, "apprehendere", to seize. "Apprehendere" is also the source of English apprehend.

Apprehensive means, anxious or fear; uneasy.