sign-out (n., adj.); sign out, sign out of (v.): As a noun or an adjective, it’s hyphenated. As a verb, it’s two words, which may be followed by the preposition of.

sign-up (n., adj.), sign up (v.): Hyphenate when used as a noun or an adjective. Two words when used as a verb. (Examples: Sign up for the service. Fill in the sign-up form. Sign-up is free.)

since: Not a synonym for “because.” Can be confused with the sense of “over the time that has passed” rather than “as a result of.” Use because instead of since when possible. Also applies to “due to” and “owing to” and “due to the fact that” and other, needlessly wordy ways of saying because.

site map: Two words.

slideshow (n., adj.): One word.

smartphone: One word.

SMB: Abbreviation for small and medium-size business (plural: SMBs).

SMO: Abbreviation for social media optimization.

social CRM: The word “social” here is lowercase. Abbreviation for social customer relationship
management, usually in regard to software platforms.

social network (n.), social-network (adj.): Two words when used as a noun. Note hyphen when used as an adjective. (Examples: Social-network analysis is a key technique in modern sociology. Add contacts to expand your social network.)

social networking (n.), social-networking (adj.): Note hyphen when used as an adjective. Two words when used as a noun. (Examples: The social-networking phenomenon has really taken off. To attract users, the site added social networking.)

software-as-a-service: Lowercase; hyphenated (abbreviation: SaaS).

spam (n., adj., v.): Lowercase when referring to unsolicited email or the act of sending such email.

startup (n., adj.), start up (v.): One word when used as a noun or an adjective (not hyphenated). Two words when used as a verb.

swag: Free goods. Not schwag or shwag.

text (n., v.): Short form of text message. Plural: texts. Other forms: texted, texting. (Examples: Did you get my text? Don’t text while driving. She was texting during the lecture.

text message (n.): Two words when used as a noun. Note hyphen when used as an adjective or a verb. (Examples: She had a heated text-message argument with her boyfriend. Did you get my text message? I’ll text-message you with the details.)