29 U.S. Code § 152 - Definitions
When used in this subchapter—
(1) The term “person” includes one or more individuals, labor organizations, partnerships, associations, corporations, legal representatives, trustees, trustees in cases under title 11, or receivers.
(2) The term “employer” includes any person acting as an agent of an employer, directly or indirectly, but shall not include the United States or any wholly owned Government corporation, or any Federal Reserve Bank, or any State or political subdivision thereof, or any person subject to the Railway Labor Act [45 U.S.C. 151 et seq.], as amended from time to time, or any labor organization (other than when acting as an employer), or anyone acting in the capacity of officer or agent of such labor organization.
(3) The term “employee” shall include any employee, and shall not be limited to the employees of a particular employer, unless this subchapter explicitly states otherwise, and shall include any individual whose work has ceased as a consequence of, or in connection with, any current labor dispute or because of any unfair labor practice, and who has not obtained any other regular and substantially equivalent employment, but shall not include any individual employed as an agricultural laborer, or in the domestic service of any family or person at his home, or any individual employed by his parent or spouse, or any individual having the status of an independent contractor, or any individual employed as a supervisor, or any individual employed by an employer subject to the Railway Labor Act [45 U.S.C. 151 et seq.], as amended from time to time, or by any other person who is not an employer as herein defined.
(5) The term “labor organization” means any organization of any kind, or any agency or employee representation committee or plan, in which employees participate and which exists for the purpose, in whole or in part, of dealing with employers concerning grievances, labor disputes, wages, rates of pay, hours of employment, or conditions of work.
(6) The term “commerce” means trade, traffic, commerce, transportation, or communication among the several States, or between the District of Columbia or any Territory of the United States and any State or other Territory, or between any foreign country and any State, Territory, or the District of Columbia, or within the District of Columbia or any Territory, or between points in the same State but through any other State or any Territory or the District of Columbia or any foreign country.
(7) The term “affecting commerce” means in commerce, or burdening or obstructing commerce or the free flow of commerce, or having led or tending to lead to a labor dispute burdening or obstructing commerce or the free flow of commerce.
(8) The term “unfair labor practice” means any unfair labor practice listed in section 158 of this title.
(9) The term “labor dispute” includes any controversy concerning terms, tenure or conditions of employment, or concerning the association or representation of persons in negotiating, fixing, maintaining, changing, or seeking to arrange terms or conditions of employment, regardless of whether the disputants stand in the proximate relation of employer and employee.
(10) The term “National Labor Relations Board” means the National Labor Relations Board provided for in section 153 of this title.
(11) The term “supervisor” means any individual having authority, in the interest of the employer, to hire, transfer, suspend, lay off, recall, promote, discharge, assign, reward, or discipline other employees, or responsibly to direct them, or to adjust their grievances, or effectively to recommend such action, if in connection with the foregoing the exercise of such authority is not of a merely routine or clerical nature, but requires the use of independent judgment.
(12) The term “professional employee” means—
(a) any employee engaged in work
(i) predominantly intellectual and varied in character as opposed to routine mental, manual, mechanical, or physical work;
(iii) of such a character that the output produced or the result accomplished cannot be standardized in relation to a given period of time;
(iv) requiring knowledge of an advanced type in a field of science or learning customarily acquired by a prolonged course of specialized intellectual instruction and study in an institution of higher learning or a hospital, as distinguished from a general academic education or from an apprenticeship or from training in the performance of routine mental, manual, or physical processes; or
(b) any employee, who (i) has completed the courses of specialized intellectual instruction and study described in clause (iv) of paragraph (a), and (ii) is performing related work under the supervision of a professional person to qualify himself to become a professional employee as defined in paragraph (a).
(13) In determining whether any person is acting as an “agent” of another person so as to make such other person responsible for his acts, the question of whether the specific acts performed were actually authorized or subsequently ratified shall not be controlling.
(14) The term “health care institution” shall include any hospital, convalescent hospital, health maintenance organization, health clinic, nursing home, extended care facility, or other institution devoted to the care of sick, infirm, or aged person. 
 So in original. Probably should be “persons.”
Source(July 5, 1935, ch. 372, § 2,49 Stat. 450; June 23, 1947, ch. 120, title I, § 101,61 Stat. 137; Pub. L. 93–360, § 1(a), (b),July 26, 1974, 88 Stat. 395; Pub. L. 95–598, title III, § 319,Nov. 6, 1978, 92 Stat. 2678.)
References in Text
The Railway Labor Act, referred to in pars. (2) and (3), is act May 20, 1926, ch. 347, 44 Stat. 577, as amended, which is classified principally to chapter 8 (§ 151 et seq.) of Title 45, Railroads. For complete classification of this Act to the Code, see section 151 of Title 45 and Tables.
1978—Par. (1). Pub. L. 95–598substituted “cases under title 11” for “bankruptcy”.
1974—Par. (2). Pub. L. 93–360, § 1(a), struck out provisions which had excepted from definition of “employer” corporations and associations operating hospitals if no part of the net earnings inured to the benefit of any private shareholder or individual.
Par. (14). Pub. L. 93–360, § 1(b), added par. (14).
1947—Act June 23, 1947, amended section generally to redefine terms used in this subchapter and to define several new terms.
Effective Date of 1978 Amendment
Amendment by Pub. L. 95–598effective Oct. 1, 1979, see section 402(a) ofPub. L. 95–598, set out as an Effective Date note preceding section 101 of Title 11, Bankruptcy.
Effective Date of 1974 Amendment
Amendment by Pub. L. 93–360effective on thirtieth day after July 26, 1974, see section 4 ofPub. L. 93–360, set out as an Effective Date note under section 169 of this title.
Effective Date of 1947 Amendment
For effective date of amendment by act June 23, 1947, see section 104 of act June 23, 1947, set out as a note under section 151 of this title.