WordNet sense 1 (having an indicated pole (as the distinction between positive and negative electric charges)):

polarity

WordNet sense 2 ((astrology) one of 12 equal areas into which the zodiac is divided):

house, mansion, house, sign of the zodiac, planetary house, star sign

WordNet sense 3 (an event that is experienced as indicating important things to come):

augury, foretoken, preindication

WordNet sense 4 (any communication that encodes a message):

signal, signaling

WordNet sense 5 (a perceptible indication of something not immediately apparent (as a visible clue that something has happened)):

mark

WordNet sense 6 (structure displaying a board on which advertisements can be posted):

signboard

WordNet sense 7 (approve and express assent, responsibility, or obligation):

ratify

WordNet sense 8 (engage by written agreement):

contract, contract, sign up, sign on

WordNet sense 9 (communicate silently and non-verbally by signals or signs):

signalize, signalise

WordNet sense 10 (mark with one's signature; write one's name (on)):

subscribe

WordNet sense 11 (make the sign of the cross over someone in order to call on God for protection; consecrate):

bless

WordNet sense 12 (used of the language of the deaf):

gestural, signed, sign-language

WordNet sense 13 (able or tending to communicate):

communicative, communicatory